WebGL build fully functional

I finally did it and managed to fix my build to work properly on WebGL! Exceptions on start are gone and the leaderboard are working.

I had to invest a small amount of money to get SSL activated on my leaderboard-service, otherwise it wouldnt work. The exception issue was easily found and was caused by a script i accidently added twice to the same object..

You can play the game in your browser here: https://vendaar.itch.io/simple-tetris

Changelog:
- Controls : you can now go down faster by holding arrow-down
- Controls: added "Go back" functionality in highscores-list by pressing 'Escape'
- Graphics: added falling blocks animations in the menu
- Backend: switched from http to https WWW requests
- Other: small bugfix on object-spawning

Known issues:
Sometimes your new score isnt shown on the list right away, wait 30 seconds or refresh manually by going back to the menu and open the Highscores again. Don't worry tho: Your score is saved even if you don't refresh again!

To Do:
- smarter rotation of blocks
- smoother horizontal movement by holding down keys
- graphic overhaul
- add sounds and options menu