bulldozer: fix adjacent roads/wires/etc. when bulldozing

This patch restores the correct bulldozer behavior regarding adjacent
roads, wires, and rails that was lost when the toolstroke series
of patches were applied.

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@768 d9718cc8-9f43-0410-858b-315f434eb58c
zoom-levels: fix to recognize the numpad "-" key to zoom out

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@769 d9718cc8-9f43-0410-858b-315f434eb58c
graphics: high-color water
graphics: make a high-color DIRT tile image
graphics: use a transparent layer to implement wires
graphics: experiment with new forest graphics (work in progress)
graphics: more work on hi-color forest
graphics: experiment with an SVG wire tile
graphics: finish work on high-color forest
graphics: use an SVG-based police station
graphics: make SVG road tiles
graphics: SVG traffic (vertical and horizontal)
graphics: implement some curved traffic as SVG images
graphics: fix curved traffic SVG animation
graphics: finish SVG traffic for all curved roads
tile declarations: experimenting with new parser for tile declarations
TODO- ideas for animation syntax
graphics: make 32px version of res_houses
graphics: an SVG residential building (straight-up projection)
notes: add some comments about tile resolution