Exception now knows what() method
More standard conformant exception handling.

We now derive from runtime_error and dropped the message member
(since it is already in std::exception).
Including file name in most of the exceptions thrown.
README.md update
Added mmap_exception.h to SOURCES and HEADERS
Fix in opening read/write private file.

We need to open it readonly, else there might be a permission problem
README.md update
Performance test with 0.5G file
2 more tests to track down performance bug.
KEEP_FOREVER flag: never close any file.
Merge branch 'open-fix'
Fixed a bug when allocating 0 bytes.
Handling deallocate(p, 0) - fixed now?
README.md update
Merge branch 'master' of github.com:johannesthoma/mmap_allocator

Conflicts:
	README.md