theme/rogue & threshold based vitals

[ondreian]

After quite a bit of subtle tweaking, it's become rather apparent that replicating SF's progress bars accomplishes nearly exactly the opposite of what we want.

The UI should make it immediately apparent when a vital is low, but progress bars are smaller and less visible the lower a value becomes.

Going forward I think it makes sense to use threshold based versions and move away from how SF does this everywhere, but this initial PR is just for vitals.

closes #88

[ondreian]

Also fixed negative vital display

[chriscoyier]

Good to go 💪

[ondreian]

Themes will now work the same way as userCSS did