v0.1.9 overhauls the effort system

The effort system is now overhauled. The starting effort for each opponent in an action is no longer random, but a value that depends on the stats of the character. It can be adjusted up or down, as before. It is now possible to decrease it all the way to zero, regaining some stamina in the process. As before, increasing it takes extra stamina.

Anger is a new stat (that's currently not shown on screen) and applies to each character. Anger is gained by being exposed to one or more repeated actions during a short period of time (in practice this means spamming a limited number of actions over the course of the last 10 actions). Anger acts as a supplement to regular effort. It decreases over time, if the trigger is gone.

The fights are now more dynamic and require more attention, with the CPU character potentially increasing their effort repeatedly over the course of each action.

Improved the characters' look. 

Improved the bars look.

Several small fixes.