Make sound design more consistent, beautify pickup orbs, and fix a bug

All SFX are now 8bit courtesy of LSDJ, pickup orbs look like PURE ENERGY, and fixed a bug which prevented selection of a tower behind another tower.
Add prefab for first level introduction
Add all level intro emails
Merge with Aaron's branch
Change UI sounds again
Created a working presence bar and an updated version of the UI prefab to reflect that.
Merge with Ricky's branch

one billion years in Vim
Begin beautifying UI
Begin implementing aesthetic UI
make UI colors more consistent
UI v2.0. Probably needs one more revision.
UI complete visually
Fix dumb ui stretching
Make UI panel scrolling smoother