Digging/Building/Tracing

In shorts, now players can build/digging structures, it`s test feature with some of known issues:
1. only few types of blocks could be placed (droplist at the bottom of the screen)
2. if you remove/obscure light emitting block (pumpkin), light will not be recalculated
3. All building stored in memory, so, don`t build too much, since it could be lost once server restarted

Beside building/digging i also manage to implement client side tracing, which actually move virtual block alongside tracing ray