* Added customisations and README
* Tweak keymap: word traversal/deletion
* Add w and b word traversal/deletion keycodes.
* Add fine volume control key codes, but don't use them, because they
conflict with other key codes. `A` somehow got remapped to fine
volume up.
* Set mousekey delay to zero
* Use SAFE_RANGE for key codes.
* Update keymap and README
Add new mouse-specific layer 3, activated by pressing and holding space.
Add brightness controls to layer 4 (previously, layer 3).
Update README:
* New keyboard-layout mockup image.
* Add actual link to kbdfans.cn.
* Update layer descriptions.
* Fix indentation in keymap.c
* Use _______ over KC_TRNS to increase readability
* Custom keys: use #define over process_record_user
* Use enum for naming layers
* Rename README.md -> readme.md
