scope.sh: added exiftool
gui.ui: catch an exception with surrogates in "update title" code
shorten all copyright messages for better readability
ext.human_readable: added comment
defaults/options: add __pycache__ to hidden files
data/mime.types: use spaces instead of tabs, line them up
implemented "rifle", a new file launcher

ranger/ext/rifle.py is a standalone program that works without ranger.
The configuration is not in python anymore, thus is easier to
understand, modify and parse.
ext.get_executables: speed optimization
removed code of old file-opener system
container.tags: typo
ext.rifle: added hooks, fixed bugs.
defaults/rifle.conf: added documentation
ext/rifle.py: added documentation and cleaned up
defaults/rifle.conf: improved, reordered
ext.rifle: make it executable. not sure if that's a good idea.
ext.rifle: added main() function
ext.rifle: polishing
core.runner: updated ALLOWED_FLAGS, added comment
ext.rifle: fixed hook_environment
setup.py: added entry for rifle.conf