Add Caps Lock ↔ Return support

[ZevEisenberg]

Not sure if Return should work like a Caps Lock toggle, but Caps Lock should definitely map to Return.

Questions: what if you have Caps Lock mapped to something else, such as Control, as many people do? Can we detect that? Can we deal with it? Is it easier to just advise that you don't do that?

[ZevEisenberg]

A spot of research reveals that the key codes that are sent are those of the remapped keys, so if I have my Caps Lock mapped to Control, the event tap reports that I pressed the Control key. That could complicate things. In the meantime, we can implement sticky keys in #7.

[louiechristie]

As a workaround you can install Karabiner-Elements and map caps lock to Return key:
https://karabiner-elements.pqrs.org/docs/manual/configuration/configure-simple-modifications/

Not having a return key was a deal breaker for me.

I typed the last sentence with one hand. (Capital N was the hardest.)