Toggle numbers on/off on WinEnter/WinLeave

[mrpdaemon]

When working with multiple split windows, it makes more sense for only
the active window to be in relative number mode and for all the other
windows to be in absolute number mode.

[myusuf3]

@mrpdaemon I am not mad at you for this. I might even like it. Let me try it out and lets see what we can do.

Can you also update the documentation for its potential merger.

[mrpdaemon]

I did update the documentation, however it looks like my change doesn't work right in all cases - it only works when a new window is created with :split or :vsplit but not when its combined with opening a new buffer, ie :split or :vsplit results in the old window remaining in relative mode. I'll look deeper into this and figure out how to get it working right for those cases.

[mrpdaemon]

GitHub ate my tags there, meant that :split FILENAME or :vsplit FILENAME doesn't work right.

[mrpdaemon]

Nevermind my previous two comments, the problem was due to a development version of MiniBufExpl which for some reason screws up with WinEnter and WinLeave events. The change works fine with the stable version of MiniBufExpl or without MiniBufExpl, so this should be good to merge if you like the behavior.

[sethfowler]

I'm glad to see there's demand for this from more than just me. My pull request #27 also adds this feature. I used BufEnter and BufLeave instead of WinEnter and WinLeave, though.

[myusuf3]

@mrpdaemon @Sfowler This will likely be the on that I merged so I am going to close the other. I just need to make sure it works before I merge it in.

[RyanMcG]

👍 This PR works for me. In fact I've merged it into the development branch of my fork and have been using it happily.

See RyanMcG#2 and my development branch.