Added DW_INT_TO_POINTER/DW_UINT_TO_POINTER/DW_POINTER_TO_INT/DW_POINTER_TO_UINT macros. These are used to cast between pointer and integers without generate warnings on 64bit systems. Converted Mac source and dwtest source to use them. Not sure if limits.h is available on all target platforms, will commit fixes as necessary.

This is a file just to keep this directory in existance in CVS.