Fixed issue #1994: created new subclasses to manage vertex and edge types
Fixed issue #1996 about supporting inheritance on edge traversing
Merge branch 'develop' into rid-set-sbtree

Conflicts:
	graphdb/src/main/java/com/tinkerpop/blueprints/impls/orient/OrientBaseGraph.java
	graphdb/src/main/java/com/tinkerpop/blueprints/impls/orient/OrientVertex.java