Add sleep when saving zoomed windows

When saving zoomed windows:

- window is un-zoomed
- window layout snapshot is taken
- window is zoomed back

This is done because otherwise tmux does not provide correct window
layout. With this we're working around a tmux bug really.

The above causes an issue with vim. For some reason vim cannot properly
reload it's content when "un-zoom + zoom" is done quickly. Everything
works ok if a little sleep/wait is added, so we're doing just that.
0.1 second sleep seems to be enough.

About `sleep 0.1 || sleep 1`: this is a hack. We want to wait for 0.1
seconds, which seems to be enough to fix the issue. However, according
to POSIX, `sleep` command takes only integers.
BUT, decimal values seem to work everywhere. So, we're using a decimal
value, and if that fails, we behave POSIX friendly.

Related to issue #112.

scripts/save.sh

@@ -224,6 +224,8 @@ dump_windows() {
 				toggle_window_zoom "${session_name}:${window_index}"
 				# get correct window layout
 				window_layout="$(tmux display-message -p -t "${session_name}:${window_index}" -F "#{window_layout}")"
+				# sleep required otherwise vim does not redraw correctly, issue #112
+				sleep 0.1 || sleep 1 # portability hack
 				# maximize window again
 				toggle_window_zoom "${session_name}:${window_index}"
 			fi