Create rlw-stub.sh

Stub is used to automatically update the launcher from GitHub if installed to the system.
Backported updater

Backported self-update function from 2.1-SNAPSHOT to 2.0, will automatically update if installed to ~/.rlw
Fixed a few typos
depcheck should run in a reasonable order
Made some syntax prettier.
Merge pull request #4 from alfonsojon/2.0-stub

2.0 stub