v0.80 Devlog

v0.80 introduces the game's hard mode - which is way overtuned at the moment!

Major changes:

- New Hard level with new background and music

- Added RSV pathogens and a new cell to swap to in the new level which fires RSV antibodies.

- Added a new pathogen destruction animation and slightly extended the existing flu and SARS animations (0.5 > 0.6 second animation)