Changing the GUID implementation to Boost UUID

guid_malloc was renamed to guid_new_ptr_return, and references were updated.
guid_to_string was deprecated, but still being used. Some references were corrected,
    and others were changed to guid_to_string_buff as it seemed meet.
guid_new was renamed to guid_replace to match its function. references were updated.
guid_shutdown and guid_init were removed; references were updated.
Some new GUID tests were added.
md5.* was removed and the build system was updated.
Documentation in guid.h was updated.
Many of the guid tests were updated.