Document bug fixes and new features

[goldstar611]

Bug fixes

• error with gl switch in non existant directory gitless-vcs/gitless#118
• Partial fix: gl diff: not working with diff-so-fancy or delta gitless-vcs/gitless#241
• Smooth out the Set Upstream workflow gitless-vcs/gitless#165
• gl status fails after resetting head of branch gitless-vcs/gitless#195, Crash when tracking a deleted file gitless-vcs/gitless#162
• gl commit: no option -s to sign-off gitless-vcs/gitless#238
• Bug in gl switch -mi #7
• gl crashes in repo with no commits #10
• repo directory is always double slash #13
• git mv causes OSError index does not contain <file> #17, Fixes fuse error gitless-vcs/gitless#231, Fixes error running - gl commit  gitless-vcs/gitless#153, Fixes commit fails after file rename gitless-vcs/gitless#63
• Ask to create remote instead of failing #16
• gl history stats show zeros #12

New Features

• git-worktree support
• partial support for custom core.pager in gl history
• gl ignore -g pattern -c "comment"
• gl remote --update url
• gl commit --sign-off
• git pre-commit hook (not gl commit compatible 😢 )
• alias gl push to gl publish
• alias gl log to gl history
• Ask to create remote branch if not exists
• gl fetch is a git fetch wrapper
• gl pull is agit pull wrapper

Todo

• Keep man page up to date
  • https://bugs.python.org/issue14102
  • http://notes.secretsauce.net/notes/2018/10/07_generating-manpages-from-python-and-argparse.html

Wont fix / Cant fix

• Shallow and --depth clones #20