remove unused settings.py

backout config.read_only as a useless feature

relocate the new exif module to lib/, as it's not really part of degal as such

change exif.py:main to take multiple paths

add support for sub-IFDs, kind of hacky

refactor exif_data to use a Tag class for each tag, instead of a magic tuple

tidy up exif_data a bit

new exif.py seems to work now, although still missing sub-IFDs

initial exif.py code

split --force-update into --force-thumb/--force-html options, implement for main

fix folder_page template

add default title for folders

modify EXIF.py to use mmap in the hope of slightly better improvements with less syscalls

implement simple stat caching using lazy_load for filesystem

fix LazyProperty to not inherit from property, so as to act as a non-data descriptor, which can then be overriden by per-instance __dict__ values

fix Thumbnail.stale/File.older_than behaviour

slightly reoriganize function structure in commands.main

fix File.newer_than/File.older_than to correctly handle None

move Command exception handling into command.py, and handle KeyboardInterrupt

change Image.update to unconditionally update the thumb/preview

fix Folder.subdirs

add task_threads config setting

initial implementation of threaded rendering of a folder's images

implement up-to-date checking for commands.main, and add --force-update option

remove obsolete req.py

move thumbnail rendering from render.py to thumbnail.py, and implement staleness checking for Images, plus index_images for Folder

change utils.LazyProperty to store the cached value using obj.__dict__

fix templates to show thumbnails on folder template

fix Gallery.stylesheet to actually copy it into place

misc. format.py formatting bugs