This is the command invoked repeatedly to make the changes:
:%s/^\(.*\)|\%(\*\(\d\+\)\)\?$\n\1|\%(\*\(\d\+\)\)\?$/\=submatch(1)..'|*'..(max([str2nr(submatch(2)),1])+max([str2nr(submatch(3)),1]))/g
In non-multigrid UI the only change is that the returned height now
excludes winbar, and this is compatible with Vim.
In multigrid UI this means the return value of these functions now
reflect the space available for buffer lines in a window.
No change in nvim_win_get_height() and nvim_win_get_width().
Previously, there was a bug where setting the local value of 'winbar' to
itself would cause winbar to appear on a floating window, which is
undesirable. This fix makes it so that it's explicitly required for the
window-local value of 'winbar' for a floating window to be set in order
for winbar to be shown on that window.
