Move all of the macros to their own file.

This commit makes the following changes:
1. Create leornian_memory.h, a header file for working with a
libleornian memory file.
2. Move all of the basic bit manipulation macros to leornian_memory.h.
3. Move all of the memory statement macros to leornian_memory.h.
4. Move the leo_mem() function declaration and its macros from
leornian.h into leornian_memory.h.
5. Add an apporpiate install() call to CMakeLists.txt to install
leornian_memory.h into the system include directory.

These changes will reduce clutter from the core interface, and make it
possible for other programs to interface with memory files by simply
including leornian_memory.h.