DX: colorize sphinx-build output (#33)

* DX: pass all environment variables in `tox` config

* MAINT: sort config keys in `tox.ini`

tox.ini

@@ -1,5 +1,4 @@
 [tox]
-passenv = PYTHONPATH
 skip_install = True
 skip_missing_interpreters=true
 skipsdist = True
@@ -9,16 +8,14 @@ envlist =
   sty,
 
 [testenv]
-description =
-  Run all fast unit tests
 allowlist_externals =
   pytest
 commands =
   pytest {posargs:tests}
+description =
+  Run all fast unit tests
 
 [testenv:cov]
-description =
-  Compute the test coverage of all unit tests
 allowlist_externals =
   pytest
 commands =
@@ -28,10 +25,10 @@ commands =
     --cov-report=xml \
     --cov=boostcfg \
     --cov=pawian
+description =
+  Compute the test coverage of all unit tests
 
 [testenv:doc]
-description =
-  Build documentation and API through Sphinx
 allowlist_externals =
   sphinx-build
 commands =
@@ -41,10 +38,13 @@ commands =
     -TW \
     -b html \
     docs/ docs/_build/html
+description =
+  Build documentation and API through Sphinx
+passenv = *
+setenv =
+  FORCE_COLOR = yes
 
 [testenv:doclive]
-description =
-  Set up a server to preview changes to the HTML pages live
 allowlist_externals =
   sphinx-autobuild
 commands =
@@ -56,24 +56,25 @@ commands =
     --re-ignore docs/api/.* \
     --open-browser \
     docs/ docs/_build/html
+description =
+  Set up a server to preview changes to the HTML pages live
+passenv = *
+setenv =
+  FORCE_COLOR = yes
 
 [testenv:docnb]
-description =
-  Execute Jupyter notebooks and build documentation with Sphinx
 allowlist_externals =
   sphinx-build
-passenv =
-  TERM
-setenv =
-  EXECUTE_NB = yes
 commands =
   sphinx-build -nW --keep-going -b html docs/ docs/_build/html
+description =
+  Execute Jupyter notebooks and build documentation with Sphinx
+passenv = *
+setenv =
+  EXECUTE_NB = yes
+  FORCE_COLOR = yes
 
 [testenv:linkcheck]
-description =
-  Check external links in the documentation (requires internet connection)
-passenv =
-  EXECUTE_NB
 allowlist_externals =
   sphinx-build
 commands =
@@ -82,11 +83,16 @@ commands =
     -T \
     -b linkcheck \
     docs/ docs/_build/linkcheck
+description =
+  Check external links in the documentation (requires internet connection)
+passenv = *
+setenv =
+  FORCE_COLOR = yes
 
 [testenv:sty]
-description =
-  Perform all linting, formatting, and spelling checks
 allowlist_externals =
   pre-commit
 commands =
   pre-commit run {posargs} -a
+description =
+  Perform all linting, formatting, and spelling checks