Patch "Push".3

This patch is far more substantial than the previous two. Following things were added or changed:

• Continuous movement: You can now (finally) hold down a movement button to keep moving in that direction. The system is not entirely bulletproof yet, but there should be no extremely obtrusive bugs. If you do find issue using the continuous movement, button-mashing still works too (and is unchanged).
• Continuous undoing: You can now (also finally) hold down any undo button to continuously undo until the button is released. As of now, there is a tiny delay between the first and second undo. This is by design; do let me know if this is more of an inconvenience.
• Smart(er) undoing: The game will now not track any "empty" moves for the purpose of undoing them. Concretely, this means it'll skip over any moves you spend running into things without moving them.
• Saved data has been involuntarily reset yet again (sorry!), but it should be the last time this happens. Moving forward, it should persist even between different updates. Do still note that they can still reset when clearing cache!
• "Pillar" has had yet another revision to patch out an unintended solution which didn't use one of the doors.
• Lowered the volume of a certain sound effect.
• Fixed a bug involving the background music changing when looking at a wall.