The Survival High Score-update!

Please carefully skip reading this if you are not interested in change logs.

NEW things added:
- survival high score display on the main screen (if you ever tried Survivor Mode).
- WASD-controls added.

I have also changed and tweaked some things
- The row-highlight of where the cursor is now disappears more slowly.
- Demo version: clicking on non-playable things, now also shows visual feedback.

And I secretly fixed some mistakes I hope nobody saw
- When turned off in the option screen, the music came back after finishing a level.
- The music was confidently playing at the titlescreen if music was turned off.
- Sometimes a block wouldn't fall down, because it was touching the edge of another block (in another row).
- Survival mode always boasted your achievement by saying you had a high score. This was not always true. I made it stop lying.