Extend by more semantic extensions in SMW repo

[kghbln]

Since the semantic extension now transit to extension registration we might as well add more extensions. Thus people will be able to use them at their liking, meaning that the code is already there to be invoked or not.

• SBL 2.x - already supporting extension registration
• SESP 2.x - already supporting extension registration
• SCI 2.x - already supporting extension registration
• SG 3.x - already supporting extension registration + Lingo
• SIL 2.x
• SMT 2.x

I will wait for SIL and SMT to be ready to support extension registration before doing this.

[kghbln]

We should probably add in all extensions which are now part of the https://github.com/SemanticMediaWiki/SemanticBundle. Will do so after the 3.1.0 release of SMW.