Check file args: 4 unique must exist with writable result.

For v1.0.0-RC3 - boot, startup defaults, defer report config isues.

During boot don't try to access logging if logging didn't init.
During startup handle a default highlight not available.
Don't report config issues until startup is fully complete.

For v1.0.0-RC2. Flip args for bind_extra.

Prep for 1.0.0-RC1

Report 'No change' if use hunk does not change result.

Polish up the help.
Fix minor bug that left current conflict highlighted when moving off it.

Doc, wiki, images.

Release plugin/splice.vim

Make "D: diffs off" a toggle.

Add installation instructions to readme. 0.9-RC1