Add visual flair

Add particle effect for enemy death, as well as sounds for tower shooting and enemy death. Move some things around into new subdirectories. Create base tower prefab.
Change enemy behavior script to spawn death animation on death
Add sound files
Merge branch 'master' into christian_staging
Create base email gimmick and email response script skeleton.

Also add a new folder for fonts.
Merge with aaron_staging
Commit previously unsaved changes. Oops.
Add new death animation for second enemy type

Same as the original but green. Also tweak the red death animation to look a bit better.
Add friend request gimmick, improve email gimmick

Add animations to reply and delete buttons.
Delete duplicate prefab, rename gimmick script

Also did a little bit of directory refactoring.
Complete gimmick skeletons

Also did some organization as usual.
Make friend request gimmick scalable
Create script to randomly select email contents

Contents are based on whether or not the email is marked good or bad.
Add script to randomly populate friend request gimmicks

still needs to populate the profile picture element.
Add script to populate download gimmick text fields.
Merge branch 'christian_staging' into master
Ignore MonoDevelop userprefs
Add game state enum, waves may only start after last wave is over