Setting version to 0.7.1:

The most significant improvements are in properties and untyped graph. Apart from this we have now near-perfect access modifiers and if a field/method can be final, it is so.

#### Properties

- Properties have now arities on both sides
- we have get and getOpt methods, with get requiring ToOne
- removed TypedGraph unique/non-unique property classes, now you can user arities directly for that

#### Untyped graph

- fixed untyped transactional graph inheritance, which was backwards; now Transactional extends UntypedGraph
- added a Transaction interface

version.sbt

@@ -1 +1 @@
-version in ThisBuild := "0.8.0-SNAPSHOT"
+version in ThisBuild := "0.7.1"