tools: update MapPatcher.jar, add mapclean helper

MapPatcher.jar will now run interatively when merging, prompting you
when it finds a conflict.
Added a clean_map_git.sh file that will automatically clean maps
without needing a prepare_map.bat call beforehand. Needs to be run in
git bash, or have .sh associated with something that has git.
Fixed line endings in install.txt to show up right in notepad.