Open TD v1.0.0: The mobile update

This update makes various changes to make the game playable on mobile:

• Update all menus to work on smaller screens (adding scrollbars and truncating where necessary)
• Update the HUD to also fit mobile screens
• Make sure all actions can be performed using a touchscreen
• Rewrite the world rendering to use webGL 1.0 for better compatibility

There are also some small bugfixes, the ui now uses sprites instead of emojis and I made an actual logo.
With that I've also decided to make this the 1.0.0 release.

Have fun!