Added multiple block types

In the process I added a new texture (ripped from some minecraft skin),
and fixed a bug where the chunks still loaded at program termination would
not be saved to disk.
preparations for chunk recycling

chunk.cc was made private non-const and all allocations of Chunk were
moved to the chunk loader
implemented chunk loader chunk pool, but deactivated

the allocation of new chunks does not seem to be a bottleneck and can be
activated once it becomes a problem.
Merge branch 'variable_chunk_render_distance' of git://github.com/Speedy-Consoles/3dgamecpp into variable_chunk_render_distance

Conflicts:
	src/render.cpp
added orientation checking block
fixed chunks not being saved on program termination
reorganized includes to make compilation faster
changed Makefile to allow a folder tree
added setblock to serverinterface and fixed face rotation
Merge branch 'variable_chunk_render_distance' of git://github.com/Backson/3dgamecpp into variable_chunk_render_distance