Display is now correctly updated with fixed fps.

[MKesenheimer]

Changes for slower display refresh rate

Description

The e-ink display is updated very frequently whenever the state of the pwnagotchi changes.
This effectively makes the config parameter ui.fps useless as changes of the state are more frequent than the refresh rate. I think a too high refresh rate is bad for the display, so I would like to give users the opportunity to change how often the display is refreshed.

With the new code, the display is not refreshed under a fixed time that is given by the parameter ui.fps:

time = 1.0 / ui.fps

However, the caveat is that not all states and information are displayed and some information will therefore be lost.
The user has still the possibility to choose ui.fps = 0 (default) which shows all states and does not suppress information.
Note that the web interface is not affected by this limit of the refresh rate. In the web-ui still all states and information are shown. So if in doubt, what the device is doing, the user can check the web-ui.

Motivation and Context

Solves the issue that ui.fps does not have much influence on the refresh rate.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s