2.1 Alpha update.

Heyo! New game update time. I've been sitting on this one for a while now, so I don't remember quite everything that's been changed.

• Added flower mimic enemy.
• Rewrote biome variation code.
• Added some biome-specific structures.
• Upgraded the built-in structure editor.
• Added a handful of dev tools for myself.
• Rewrote the menu UI.
  • Currently, the world creation screen doesn't let you type into the world name bar. I'll fix this soon.
• Rewrote zombie enemy code.
• Redrew a bunch of unsatisfactory textures. Some are almost better.
• Optimized and rewrote large portions of the code base.
• Tweaked mechanics of sword-type weapons.
• Tweaked bomb explosion mechanics.
• Added an indicator that appears when entities take damage
• Redid the surface ambience. New clouds, and starry night, as well as a neat sky color transition.
• Added some more console commands (ability to change time, change tickrate of game, etc.)
• Fixed a huge list of bugs.
• Some items were given their own textures rather than color swaps.
• Made some items craftable that I forgot about.