Added method for custom breaking animation

Args:
Int: Side of the aniamation
Int: Metadata of the block
```
IIcon[] icons = block.getDestroyIcons(...);
icons = icons != null ? icons : this.field_94141_F; // could be inlined into \/
this.field_147592_B.func_147792_a(..., icons[destroyblockprogress.func_73106_e()]);
```
That would both, minimize the patch size and memory usage. ``Block.registerDestroyBlockIcons`` should be an empty method by default, people can override it for custom icons if they want to.