Consider to (optionally) drop some bits that are not used in the keymap, e.g. key types and interprets. Indeed, they would not impact the behavior of the resulting keymap in the client, but could cut a bit the serializing/parsing time. We should probably keep all the keycodes though, even if not mapped.

Together with #640, this would create a “minimized” serialization of the keymap.

I would make it the default, except in tools where we want to have the whole keymap by default.

Another approach is to do it at compilation time, and then rely on making all properties explicit. But I am not sure it makes the keymap serialization shorter or later parsing faster though.