[Freeciv-Dev] (PR#12362) gui_rect_iterate doesn't work for unaligned tilesets

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=12362 >

The new gui_rect_iterate requires that classic tilesets be a multiple of 
2 in dimension, and iso/hex/iso-hex tilesets be a multiple of 4 (in both 
directions).

This means engels doesn't work anymore.

It could be fixed, either by using floating-point match in 
gui_rect_iterate or by doing division more carefully (which 
unfortunately means a lot of duplicated writing).

This quick-and-dirty patch does the latter.  Is this worthwhile?

-jason