[Keyboard] Add new keyboard: Omnikeyish - A replacement PCB for the Northgate Omnikey family (#6167)

* Add omnikeyish keyboard support.

* remove out of date comment

* PCB Rev 1.1 moved Row5's pin to E6, because the teensy++ hangs an onboard LED off D6.

* Move string.h include to .c file

* Add pcb kicad link.

* Add info.json

* Move macro programming to numlock's keyposition, the most useless key on the post model M layout. Force numlock enabled on host at init time, so you're not stuck without a numpad (hopefully)

* Make the macro blink function toggle LEDs from their previous state.

* Use incorrect but code style compliant opening curly bracing style.

* Make PCB rev 1.1 the default Omnikeyish config, as the author has the only rev 1.0 boards that'll ever be.

* Fix silly spelling error in 3 defines

* First set of review changes.

* Layout macro and keymap defined using it.

* Layout macros for the northgate factory plates.

* minor rearrangements

* ALL the layouts.

* Forgot ultra-t in info.json

keyboards/omnikeyish/readme.md

@@ -0,0 +1,14 @@
+Omnikey(-ish)
+===
+
+A replacement PCB for Omnikey keyboards. (In theory) supports 101, 102, Plus, Ultra T, Ultra, Prime and Stellar, as well as customs.
+
+Keyboard Maintainer: QMK Community and Henrik O. Sørensen  
+Hardware Supported: Omnikey(-ish) PCB  
+Hardware Availability: https://github.com/henrikosorensen/keyboard_pcbs/tree/master/omnikeyish_pcb
+
+Make example for this keyboard (after setting up your build environment):
+
+    make omnikeyish:default
+
+See [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) then the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) for more information.