* Refactor layout macro names
Update the names of the layout macros to reflect QMK's desired usage.
- KEYMAP renamed to LAYOUT
- colinta keymap updated accordingly
- KC_KEYMAP renamed to LAYOUT_kc
- mtdjr keymap updated accordingly
* Update xd75.h to use #pragma once include guard
* Update keymaps to use QMK_KEYBOARD_H
* Refactor default keymap
- updated to use layout macro
- remove deprecated action_get_macro function
- add functions from QMK keymap.c template
- process_record_user
- matrix_init_user
- matrix_scan_user
- led_set_user
* Update supporting files
- updated config.h files to use #pragma once include guard
- remove errant QUANTUM_DIR code block
* Rename readme files to fully lowercase filenames
* Restructure keyboard readme
Updated the readme to better align with the current QMK template.
* Bugfixes to supporting files
