[Freeciv-Dev] (PR#7375) Unify some mapview code

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=7375 >

> [i-freeciv-lists@xxxxxxxxxxxxx - Wed Feb 04 15:11:17 2004]:
> 
> 
> With the new canvas_store_{create,free} function it is possible to
> remove some more code.

I like it a lot.

[Looking at version 3.]

Even if the tile width is not changed, we should still update the width
and height.  These values are stored accurately in the mapview struct
and may someday be used for more accurate judgements (like in animation).

I'd also really like to see support for Win32 and SDL clients before we
apply it...

jason