Rename to ydiff

Add env varirable CDIFF_OPTIONS to hold default options

More robust parser to tolerate evil unified diff

Diff of diff; solarized color

Fix TypeError exception in auto width logic

Auto width with -w 0; smooth scrolling with less --shift 1

Respect $LESS, python 3.4 and curl -L

Handle interrupts; default encoding and nonblocking I/O fix

Enahanced option parser now pass unknown option down

Fix issue ymattw#23 with --no-ext-diff