Added comments
* XML documentation for TypeUse and AbstractUse
* License header for AbstractUse
Changed AbstractUse to be a generic class where the type parameter is the "definition" object being used (variable declarations, type definitions, etc).
 * Added new FindMatches() and Matches(DEFINITION) methods to all of the AbstractUse children.
* Modified TypeInventoryTest to test the new "FindMatches" function.
Merge branch 'topic-data-incrementalupdate' of github.com:abb-iss/SrcML.NET into topic-data-incrementalupdate