* update grid alignment of keycodes
* update key assignments on via keymap
A seemingly-misplaced key assignment on Layers 1 through 3 of the via keymap led to keys being off by one in comparison to the default keymap.
* switch Backslash and Backspace on via keymap base layer
Matches the via keymap's key mapping to that of the default keymap.
* use QMK 3-character notation in oxalys80.h
* add matrix diagram; remove Planck reference
* add LAYOUT_tkl_ansi and LAYOUT_tkl_ansi_wkl layout macros
* add LAYOUT_tkl_ansi_tsangan macro
* add ISO layouts
Add LAYOUT_tkl_iso, LAYOUT_tkl_iso_tsangan, and LAYOUT_tkl_iso_wkl macros.
* enable Community Layouts support
* tidy up rules.mk
* readme tidy-up
