Document code style

Also run a stylecheck on incoming PRs, and reject the PR when the code
isn't properly formatted.

.clang-format

@@ -1,7 +1,7 @@
 ---
 Language:        Cpp
 # BasedOnStyle:  LLVM
-AccessModifierOffset: -2
+AccessModifierOffset: -4
 AlignAfterOpenBracket: BlockIndent
 AlignArrayOfStructures: None
 AlignConsecutiveAssignments:
@@ -28,24 +28,17 @@ AlignConsecutiveMacros:
   AcrossComments:  false
   AlignCompound:   false
   PadOperators:    false
-AlignConsecutiveShortCaseStatements:
-  Enabled:         false
-  AcrossEmptyLines: false
-  AcrossComments:  false
-  AlignCaseColons: false
 AlignEscapedNewlines: Right
 AlignOperands:   Align
-AlignTrailingComments:
-  Kind:            Leave
-  OverEmptyLines:  0
+AlignTrailingComments: false
 AllowAllArgumentsOnNextLine: true
 AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortEnumsOnASingleLine: true
 AllowShortBlocksOnASingleLine: Never
 AllowShortCaseLabelsOnASingleLine: false
-AllowShortEnumsOnASingleLine: true
 AllowShortFunctionsOnASingleLine: None
-AllowShortIfStatementsOnASingleLine: Never
 AllowShortLambdasOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: Never
 AllowShortLoopsOnASingleLine: false
 AlwaysBreakAfterDefinitionReturnType: None
 AlwaysBreakAfterReturnType: None
@@ -55,18 +48,17 @@ AttributeMacros:
   - __capability
 BinPackArguments: true
 BinPackParameters: true
-BitFieldColonSpacing: Both
 BraceWrapping:
   AfterCaseLabel:  true
   AfterClass:      true
   AfterControlStatement: Always
   AfterEnum:       false
-  AfterExternBlock: false
   AfterFunction:   true
   AfterNamespace:  false
   AfterObjCDeclaration: false
   AfterStruct:     false
   AfterUnion:      false
+  AfterExternBlock: false
   BeforeCatch:     true
   BeforeElse:      true
   BeforeLambdaBody: false
@@ -75,29 +67,34 @@ BraceWrapping:
   SplitEmptyFunction: true
   SplitEmptyRecord: true
   SplitEmptyNamespace: true
-BreakAfterAttributes: Never
-BreakAfterJavaFieldAnnotations: false
-BreakArrays:     true
 BreakBeforeBinaryOperators: None
 BreakBeforeConceptDeclarations: Always
 #BreakBeforeBraces: Allman
 BreakBeforeBraces: Custom
-BreakBeforeInlineASMColon: OnlyMultiline
+BreakBeforeInheritanceComma: false
+BreakInheritanceList: BeforeColon
 BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
 BreakConstructorInitializers: AfterColon
-BreakInheritanceList: BeforeColon
+BreakAfterJavaFieldAnnotations: false
 BreakStringLiterals: false
 ColumnLimit:     180
 CommentPragmas:  '^ IWYU pragma:'
+QualifierAlignment: Leave
 CompactNamespaces: false
 ConstructorInitializerIndentWidth: 4
 ContinuationIndentWidth: 4
 Cpp11BracedListStyle: true
+DeriveLineEnding: true
 DerivePointerAlignment: false
 DisableFormat:   false
 EmptyLineAfterAccessModifier: Never
 EmptyLineBeforeAccessModifier: LogicalBlock
 ExperimentalAutoDetectBinPacking: false
+PackConstructorInitializers: Never
+BasedOnStyle:    ''
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+AllowAllConstructorInitializersOnNextLine: true
 FixNamespaceComments: true
 ForEachMacros:
   - foreach
@@ -122,30 +119,20 @@ IncludeCategories:
 IncludeIsMainRegex: '(Test)?$'
 IncludeIsMainSourceRegex: ''
 IndentAccessModifiers: false
-IndentCaseBlocks: false
 IndentCaseLabels: false
-IndentExternBlock: AfterExternBlock
+IndentCaseBlocks: false
 IndentGotoLabels: true
 IndentPPDirectives: None
+IndentExternBlock: AfterExternBlock
 IndentRequiresClause: true
 IndentWidth:     4
 IndentWrappedFunctionNames: false
 InsertBraces:    false
-InsertNewlineAtEOF: false
 InsertTrailingCommas: None
-IntegerLiteralSeparator:
-  Binary:          0
-  BinaryMinDigits: 0
-  Decimal:         0
-  DecimalMinDigits: 0
-  Hex:             0
-  HexMinDigits:    0
 JavaScriptQuotes: Leave
 JavaScriptWrapImports: true
 KeepEmptyLinesAtTheStartOfBlocks: true
-KeepEmptyLinesAtEOF: false
 LambdaBodyIndentation: Signature
-LineEnding:      DeriveLF
 MacroBlockBegin: ''
 MacroBlockEnd:   ''
 MaxEmptyLinesToKeep: 2
@@ -155,7 +142,6 @@ ObjCBlockIndentWidth: 2
 ObjCBreakBeforeNestedBlockParam: true
 ObjCSpaceAfterProperty: false
 ObjCSpaceBeforeProtocolList: true
-PackConstructorInitializers: Never
 PenaltyBreakAssignment: 2
 PenaltyBreakBeforeFirstCallParameter: 19
 PenaltyBreakComment: 300
@@ -164,33 +150,27 @@ PenaltyBreakOpenParenthesis: 0
 PenaltyBreakString: 1000
 PenaltyBreakTemplateDeclaration: 10
 PenaltyExcessCharacter: 1000000
-PenaltyIndentedWhitespace: 0
 PenaltyReturnTypeOnItsOwnLine: 60
+PenaltyIndentedWhitespace: 0
 PointerAlignment: Right
 PPIndentWidth:   -1
-QualifierAlignment: Leave
 ReferenceAlignment: Pointer
 ReflowComments:  false
 RemoveBracesLLVM: false
-RemoveParentheses: Leave
-RemoveSemicolon: false
 RequiresClausePosition: OwnLine
-RequiresExpressionIndentation: OuterScope
 SeparateDefinitionBlocks: Leave
 ShortNamespaceLines: 1
 SortIncludes:    Never
 SortJavaStaticImport: Before
-SortUsingDeclarations: LexicographicNumeric
+SortUsingDeclarations: true
 SpaceAfterCStyleCast: false
 SpaceAfterLogicalNot: false
 SpaceAfterTemplateKeyword: true
-SpaceAroundPointerQualifiers: Default
 SpaceBeforeAssignmentOperators: true
 SpaceBeforeCaseColon: false
 SpaceBeforeCpp11BracedList: true
 SpaceBeforeCtorInitializerColon: true
 SpaceBeforeInheritanceColon: true
-SpaceBeforeJsonColon: false
 SpaceBeforeParens: ControlStatements
 SpaceBeforeParensOptions:
   AfterControlStatements: true
@@ -202,36 +182,36 @@ SpaceBeforeParensOptions:
   AfterRequiresInClause: false
   AfterRequiresInExpression: false
   BeforeNonEmptyParentheses: false
+SpaceAroundPointerQualifiers: Default
 SpaceBeforeRangeBasedForLoopColon: true
-SpaceBeforeSquareBrackets: false
 SpaceInEmptyBlock: false
+SpaceInEmptyParentheses: false
 SpacesBeforeTrailingComments: 1
 SpacesInAngles:  Never
+SpacesInConditionalStatement: false
 SpacesInContainerLiterals: true
+SpacesInCStyleCastParentheses: false
 SpacesInLineCommentPrefix:
   Minimum:         1
   Maximum:         -1
-SpacesInParens:  Never
-SpacesInParensOptions:
-  InCStyleCasts:   false
-  InConditionalStatements: false
-  InEmptyParentheses: false
-  Other:           false
+SpacesInParentheses: false
 SpacesInSquareBrackets: false
+SpaceBeforeSquareBrackets: false
+BitFieldColonSpacing: Both
 Standard:        Latest
 StatementAttributeLikeMacros:
   - Q_EMIT
 StatementMacros:
   - Q_UNUSED
   - QT_REQUIRE_VERSION
 TabWidth:        8
+UseCRLF:         false
 UseTab:          Never
-VerilogBreakBetweenInstancePorts: true
 WhitespaceSensitiveMacros:
+  - STRINGIZE
+  - PP_STRINGIZE
   - BOOST_PP_STRINGIZE
-  - CF_SWIFT_NAME
   - NS_SWIFT_NAME
-  - PP_STRINGIZE
-  - STRINGIZE
+  - CF_SWIFT_NAME
 ...