Declare using vim-flavor 2.0 or later
Add tests on s:snr_prefix in verbose mode
Fix s:snr_prefix to work also in verbose mode
Merge branch 'fix-snr-prefix-in-verbose-mode'

Close gh-33.
Add release notes on 0.6.3
Bump up version to 0.6.3
Merge branch 'prepare-for-0.6.3'