devel/got: update to 0.84

User-visible changes:

• add 'got histedit -d' flag to drop all commits
• add horizontal scrolling support to tog ref and tree views
• tweak 'got commit' log-message validation: now checks timestamp and size > 0
• make 'got fetch' fetch the work tree's current branch as an implicit fallback
• make 'got fetch -b branch' only fetch the named branch
• make 'got fetch' update cached HEAD symref if it has changed in remote repo
• add commit/histedit/merge/rebase -C option to commit unresolved conflicts
• make 'got status' check for merge conflict markers on newly added lines only
• ignore patterns with trailing "/" now match directories