[Freeciv-Dev] (PR#3908) gui-mui drawing code is broken

["Jason Short" <jdorje@xxxxxxxxxxxxxxxxxxxxx>]

The recent changes to the drawing code have broken gui-mui.

The biggest change needed is to remove some functions - like
update_map_canvas and functions it calls - that have been moved into the
common code.  This isn't as easy as it sounds since these functions are
wrappers that call different class functions, and it's hard to track
down everything that has become obsoleted.

Additionally some new low-level drawing functions need to be added. 
These are the gui_put_xxx functions.

Finally the mapview_canvas struct needs to be kept updated.  Currently
these values are all tracked using internal class environment variables.

Things are likely to break again when/if put_one_tile_iso is moved into
the common code.

jason