For editable views it is important to actually show the blank line so that we
can put the cursor there for typing.
This fixes problems with adding blank lines at the end of longer commit
messages.
This updates gocui to include https://github.com/jesseduffield/gocui/pull/68 and
https://github.com/jesseduffield/gocui/pull/69, which changes views to not have
an extra blank line at the end when content ending in a newline character is
written to them. This makes text views more consistent with list views, which
don't have a blank line after the last list entry either.
This doesn't improve the code much in the current state, but we'll add some more
code to this helper function in the next commit, which makes it worth it.
We haven't needed this before since we were only using the function for text in
confirmations and menus, which is unlikely to contain tabs. We are going to use
it for patches in the staging view though, which often do.
to make it more generally usable by clients other than ConfirmationHelper, which
we will do later in this branch. Rename it to WrapViewLinesToWidth while we're
at it.
Add tests; in particular, add a sanity check that we wrap lines the same way as
gocui does. The tests that are added here are the same ones as in gocui for its
lineWrap function, but we'll extend them a bit in later commits in this branch.
