UI updates

Today rolls out another load of UI reworks into the game, and we will now always attempt to refer to a user by their chosen alias rather than their identifier.

This update replaces most of the default Unity buttons /backgrounds.

I've also pushed out some initial icons for all of the research/context actions currently available, though most of these still need to be redone for some standardisation. 

The Escape key will now open the pause menu, and opening the research menu will now automatically close the context menu.