Implement shared settings menu

[chrisib]

Add a new SettingsMenu inspired by the menu system in Pam's Workout. This should give a more consistent look-and-feel to menu-oriented applications.

SettingsMenu

The SettingsMenu object contains one or more MenuItem objects. MenuItem is a generic class that can be extended as-needed to e.g. add visualizations.

Base MenuItem subclasses are SettingMenuItem, which which acts as a wrapper around a ChoiceConfigPoint, and ActionMenuItem which simply invokes a callback function based on the user's selection.

The SettingsMenu object manages button handlers for the rising & falling edge of the navigation button (b2 by default, and reads values from the navigation knob (k2 by default) as needed.

SettingMenuItems can also be configured to automatically read from ain or the non-navigation menu (k1 by default) at 10Hz and use that to automatically choose from the available choices. Each SettingMenuItem also supports callbacks when its value changes, allowing for inter-option logic, or firing other events as a result of a setting change.

An abstract MenuItem class is provided to add custom items to the menu, including visualizations (see SequentialSwitch and EuclideanRhythms for examples of visualizations implemented as menu items).

Configuration Editor

A frequently-requested feature on Discord has been a way to edit EuroPi_Config on the module itself, rather than manually editing the JSON file. This is implemented by the new tools/config_edit module. The ConfigurationEditor class implements a simple SettingsMenu to categorize the configuration points.

Items that have the potential to cause harm/usability issues if edited (e.g. changing the display SDA, SCL, Channel, or Frequency values) are marked with a new danger flag, which displays a ! warning symbol on SettingMenuItem instances that wrap them.

Modified Contrib Scripts

The following scripts have been modified to use the new SettingsMenu instead of implementing their own menu system:

• Pam's Workout
• Euclid
• Sequential Switch