Add ST_StronglyConnectedComponents.

Fixes #40. Fixes #31.
Merge branch 'fix/#15' into feature/strongly-connected-components

Again, this is to facilitate future merges.

Conflicts:
	src/main/java/org/gdms/gdmstopology/function/ST_ShortestPathLength.java
Fix function signature.
Merge pull request #54 from agouge/feature/strongly-connected-components

Add ST_StronglyConnectedComponents.