Rename `gpS` (mnemonic "pretty-signature") and `glS` ("log-signature")
to `gcv` ("commit-verify") and `glv` ("log-verify") respectivelly,
so `v` is used to verify signatures, and `s`/`S` is used to sign.
Remove `git-commit-lost` and `git-stash-dropped`, as this could be
probably joined into one function that shows all lost commits, including
lost stashes, and also because there seems to be many different ways to
do this, as discussed in https://stackoverflow.com/q/89332/2654518.
An answer worth noting is https://stackoverflow.com/a/6455586/2654518.
If someone is using this, let's discuss on a new solution...
Remove Oh-My-Zsh compatibility from `git-branch-current`, and delete
`git_current_branch`. This compatibility was already partially broken at
c1b02c0, when we also updated the gitster prompt theme. Now this
function fails when in 'detached HEAD' state (is was returning the
commit hash in this state), which is what we would expect from the use
we make of it.
Closes#244
