fix: don't minimize windows on resize

[habamax]

After window was resized use winfixwidth and winfixheight to fix window
size and run wincmd = to make all windows even (except windows with
fixed widths and heights). Unfix size afterwards.

Fixes #17 and probably fixes #19

[habamax]

[hakunin]

This does improve the usablity of the plugin as before the minimization was quite strange.
As to #19, it doesn't seem provide the option I was looking for (to make current + neighbours big and the rest tiny).

[habamax]

to make current + neighbours big and the rest tiny

Ok, looks like I missed the point there. Indeed, it doesn't solve #19

[nkakouros]

This works without animate.vim but with animate.vim enabled the issue still exists.

For instance, open vim (or nvim as in my case) with only animate.vim and lens.vim installed and open a file. Press c-w v 10 times to get 11 splits. You will see the some splits are tiny.

Of course, 11 vertical splits are pretty useless, but when the vim window is not covering the full screen the same can happen even with 3 splits.

Perhaps the same lines (that I have no idea how they solve the issue) need to be added to animate.vim's functions as well?