graphics: begin work on making source images for 3x3px tile array

git-svn-id: http://micropolis.googlecode.com/svn/trunk@907 d9718cc8-9f43-0410-858b-315f434eb58c
graphics: more 3x3px source images

git-svn-id: http://micropolis.googlecode.com/svn/trunk@908 d9718cc8-9f43-0410-858b-315f434eb58c
graphics: 3x3px versions of the road/traffic graphics

git-svn-id: http://micropolis.googlecode.com/svn/trunk@909 d9718cc8-9f43-0410-858b-315f434eb58c
graphics: use generated 3x3px tile array

git-svn-id: http://micropolis.googlecode.com/svn/trunk@910 d9718cc8-9f43-0410-858b-315f434eb58c
overlay-map: remove upper tile number limit

also- refactor a for-loop into a separate method to avoid having
code indented too far

git-svn-id: http://micropolis.googlecode.com/svn/trunk@911 d9718cc8-9f43-0410-858b-315f434eb58c