Add git ls-changed alias(es) #37

It would be very useful to modify a set of files and be able to log/ls/lsd commits which affect the modified files. I don't know offhand the best way to write this--according to this StackOverflow question, git status --porcelain can yield some useful information, and combining it with awk/cut/etc. could get that list into a useful state. git ls-files -m would list modified files, and git diff --name-only --staged would list staged files, but it'd be convenient for all modified files (staged and unstaged) to be listed, I think.