Initial work on project level IU
Completed the implementation of the project level incremental update.
1) Optimized the code for project level incremental update feature. Manually tested.
2) In SrcMLArchive.IsOutdated(), changed <= to !=, also every time a file is updated, set the srcML file's LastWriteTime to the exactly same as the source file's.
Unit tests and integration tests for SrcML Service.
No real change. Just for pull changes from the master branch.
Merge branch 'topic-incrementalupdate' of github.com:abb-iss/SrcML.NET into topic-incrementalupdate
Fixed incorrect return value from Archive.IsOutdated(). Reworded boolean expression to be more readable.
Merge branch 'master' of github.com:abb-iss/SrcML.NET