Move graph saturation detector to a sliding register of highest + lowest pressure & flow values in the chip module (~0.5% CPU load at 30 FPS)

[valeriansaliou]

This prevents each redraw to loop through all points to find the lowest/highest values. This should save some CPU cycles.

[valeriansaliou]

This should be implemented w/ the following algorithm:

• Whenever adding a data point:
• If the value is greater or lower than threshold, then:
• Update the 'has_high' or 'has_low' marker w/ the point date (override last date, even if it was in range)

On the drawer loop side:

• If there is a threshold value saved, check that date is in range, and render the saturation red lines if so