Reorganize dev scripts

This one's for @arturoc: If it's ok, i put those files in `/scripts/dev` into subfolders, cause otherwise it's pretty easy to get confused what file is for what purpose, especially if we get more in the future.
btw, what is `android_configure_arm7.sh` for? This one has some paths specific to your machine, and wouldn't it fit better into a `/scripts/android` folder?