Fixed Inventory not generating correct empty slots
Added an abs helper for Vector3
Fixed an error with the height being not set
Fixed a logic error in selecting a x/y position
Don't load abstract block classes.  This fixes the SimpleBlock problem
fixed a logic error that caused setting items to the same places.
Big cleanup and namespace adjustment

Tested this fully and things are still fine :).

Signed-off-by: Chris Sanders <zidane@outlook.com>