graphics: move "MakeTiles" program into src/ directory

(but do not include it in the generated jar file)

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@714 d9718cc8-9f43-0410-858b-315f434eb58c
build.xml: automatically build tiles.png from source images

It should work to just type `ant'.
The composed tiles.png will be generated in the 'build' subdirectory,
and automatically inserted into the generated Jarfile.

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@715 d9718cc8-9f43-0410-858b-315f434eb58c
graphics: include RearrangeTiles.java (another utility script I wrote)

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@716 d9718cc8-9f43-0410-858b-315f434eb58c
graphics: update HACKING file with new instructions for building tiles.png

git-svn-id: https://micropolis.googlecode.com/svn/trunk/micropolis-java@717 d9718cc8-9f43-0410-858b-315f434eb58c