* Adding documentation for the LM layer modifier.
This will hopefully clear up some of the confusion around adding this layer modifier. I struggled with this a bit as well at first.
* Removing duplicate table.
* Changed section title to `Changing Layers`
* Retain name
* Remove unused UNICODE(n) macro, update docs
* Add note about max length of unicode_map to docs
* QK_UNICODE_MAP → QK_UNICODEMAP
* Refactor process_unicode_map
* process_unicode_map → process_unicodemap
This is done for consistency: UNICODEMAP is the method (hence UNICODEMAP_ENABLE, process_unicodemap), whereas unicode_map is the mapping table itself.
* Update references and ordering in docs/understanding_qmk
* Add additional note to docs/understanding_qmk
* &unicode_map[index] → unicode_map + index
This avoids the issue of the compiler sometimes complaining about the array index being out of range
* Update docs/getting_started_make_guide
* Update method sections in docs/feature_unicode
* Add standard ALGR defition, remove (re)definitions from language files
* Use ALGR(kc) consistently in ALTGR(kc) aliases
* Non-Nordic keymaps should not use NO_ALGR
* Add standard KC_ALGR definition
* Update docs with ALGR and KC_ALGR
* Update SS_ALGR and ALGR_T aliases
* Adds Audio Keycodes to both the feature page and master list
* Re-orders the keycode list, so it's alphabetical (mostly)
* Add additional (missing) sections to the keycode list
* Add and update links in the keycode page
* Add and reorder links in sidebar's keycode section
* Clean up SEND_STRING keycodes and add media keys
* Remove stray define
* Add missing SEND_STRING keycodes for completeness
Also, add KC_EJCT to the keycode references
* Macro for a momentary layer switch with mods
Passes through to the existing ACTION_LAYER_MODS macro, albeit with more
limited options due to lack of space in the quantum_keycodes enum.
* Add documentation for LM layer-mod macro
* Clean up Tap Toggle documentation
