settings: File selector & other settings

First of all, TASing requires a script to play back. The user can select the parent directory at `System -> Filesystem`, next to an option to pause TAS during loads: This requires a "hacky" setup deeper in the code and will be added in the last commit.

Also, Hotkeys are being introduced: CTRL+F5 for playback start/stop, CTRL+F6 for re-reading the script and CTRL+F7 for recording a new script.