Much better drag()

No more need to pass XEvent* to handler functions
Made run_command() a normal key/button handler
No more need for CLEANMASK macro
Stable version 0.9
Fixed keyboard mappings
Revised handling of file names & paths
Corrected FSF address in license headers
Fixed hyphen-used-as-minus-sign issues in man page
Small refactorings
Uniform thumbnail selection border size

- Consistent handling of thumbnails
- Makes it easier to select very small thumbnails with mouse
Renamed key/mouse commands to indicate supported modes
Renamed application modes
Added force parameter to tns_load() to disregard cache
Put event handling back into main.c; events -> commands
Fixed include in thumbs.h
Added support for multi-frame images
Refactored img_load_gif()

- Corrected handling of transparency settings for individual frames
- Corrected handling of different frame dimensions & offsets
Added HAVE_GIFLIB macro for optional dependency on giflib
Added support for gif animation
Added command to toggle gif animations