Hash table API is now (mostly) type safe.

maildir: Moved maildir_filename_flags_*() to a separate file.

Changed .h ifdef/defines to use <NAME>_H format. --HG-- branch : HEAD

Renamed maildir_generate_tmp_filename() to maildir_filename_generate(). Also changed it to create the unique filename with time+usecs+pid, increasing usecs as needed. So there's no longer a process delivery counter. --HG-- branch : HEAD

Added maildir_filename_sort_cmp() which sorts maildir filenames by time and microseconds. Use it for sorting newly seen files. --HG-- branch : HEAD

Renamed maildir_cmp/hash to maildir_filename_base_cmp/hash. --HG-- branch : HEAD

maildir_filename_get_flags() returns void now. --HG-- branch : HEAD

Moved maildir filename related functions to maildir-filename.c --HG-- branch : HEAD