- Make Mm allocation strategy low->high by default.

- Make Mm allocation strategy low->high by default.
- Clean up Mm APIs which are not needed anymore.
- Get rid of the LOADER_HIGH_ZONE definition, now the real LoaderPagesSpanned value is calculated and used. As a result, minimum memory requirement (which was >= LOADER_HIGH_ZONE) is gone, and a maximum amount of memory which could be allocated is also gone (previously, not more that the LOADER_HIGH_ZONE).
- IMPORTANT: The FAT filesystem caching is disabled by default now due strange problems in 3rd boot stage, after switching the cache to use heap routines. Cache can't use non-heap routines anymore, since the memory will overlap the contigious modules memory space which ReactOS needs.
- More cleanup and more usage of the heap routines for temporary buffers.
- Fix a bug in MmAllocateMemoryWithType, where result of MmFindAvailablePages was checked against -1 in error case, when in reality it's 0 (spotted by Alex). NB: 0 page is marked as a reserved in x86 arch, so it's never going to be returned as an available.

svn path=/trunk/; revision=32113