[ccore] SYNC-SOM implementation

[annoviko]

SYNC-SOM should implemented in CCORE library.

Network description:

• A.Novikov, E.Benderskaya. SYNC-SOM Double-layer Oscillatory Network for Cluster Analysis. 2014.

Demands:

• Implementation should be independent from pyclustering.
• Interface should be implemented for pyclustering usage.
• pyclustering.nnet.som should provide opportunity to use core.