[optilude]

Note: This PR includes #105 (as in, the Dual Echo effect module is included here), but doesn't depend on it – I just didn't want to worry about multiple parallel branches. Please review #105 first.

There are two changes included here, under the banner of making the pedal more intuitive to use, especially when switching between effects regularly. However, they are strictly speaking independent.

1. A new "Autosave" setting, which defaults to "off". If turned on, the pedal will save automatically the current state (i.e. all effect parameters) to Preset 0 for the given effect. There is a short delay to conserve CPU, and the write operation is only done if something has genuinely changed. The net effect of this is that the pedal will appear to start up again in the same state it was when last used, and switching between effects will retain settings for each effect without an explicit "save" state.

This is how I expected the pedal to behave ("why aren't my settings saved?") – I would frequently forget to save things. It will never change any preset other than Preset 0, which is the one loaded by default when starting up or switching effects.

2. The "change effect" action is moved from the Settings menu to a new, top-level menu called Effect. When changing effects, you are immediately returned to the initial menu state (i.e. the effect name), rather than having to use the "Back" navigation.

I like this a lot better because, in my mind, "Settings" is for global settings like "true bypass" or MIDI, which are mostly "once and done", but changing effects is something you might do in normal operation. It saves a couple of clicks, and it's more intuitive to me at least that it should work this way.

As part of this change, I also moved Preset to be the second menu item, because presets belong with the current effect, and so it feels natural they come just after the first menu that contains the effect name.

[xconverge]

I hold the alternate footswitch and use the encoder for effect switching, but this change makes sense and feels normal to use so LGTM