Merge pull request #62 from pkra/v2.4-latest

updating V2.4 latest
Merge pull request #63 from pkra/v2.4-latest

updating whats-new for 2.4 release
Merge pull request #64 from pkra/v2.4-latest

More fixes for 2.4 release
fix several build warnings
adding: tutorial extension writing
remove obsolete files
Merge pull request #65 from pkra/issue57

Resolve #57