tools: update MapPatcher.jar, add mapclean helper

MapPatcher.jar will now run interactively 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 and old
dos2unix.
Fixed line endings in install.txt to show up right in notepad.

Map cleaning code in MapPatcher.jar is unchanged.