[Keymap] Added userspace for d4mation. Included their keymap for the Atreus62 (#7483)

* Added userspace for d4mation. Included their keymap for the Atreus62

* Do not assign layer numbers manually

* Remove some unneeded things per @drashna's recommendation

* Fix some single line comments I missed

* Update unicode macros to use send_unicode_hex_string() instead of process_unicode()

* OBetter check for Unicode Enabled. Moved some checks into macros.c

* Use eeconfig_init_user() to set default unicode input mode

keyboards/atreus62/keymaps/d4mation/readme.md

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+# d4mation's keymap for the Atreus62
+
+This is a bit of a work in-progress, but for the most part I like what I have done here.
+
+I switched to Dvorak some time ago and software-based support in most OS's for Dvorak isn't very great, so this keymap by default is set to Dvorak.
+
+## Table of Contents
+
+* [Layers](#layers)
+    - [Base layer](#base)
+    - [Num](#num)
+    - [Lower](#lower)
+    - [Raise](#raise)
+    - [Adjust](#adjust)
+
+# Layers
+
+## Base
+
+* By default, this layer is Dvorak. But using the Adjust layer you can switch to Qwerty
+* Double-tapping Shift enables and disables Caps Lock
+* Quickly tapping the Grave accent key will output a Grave Accent, but holding it for 200ms will output the ESC key instead
+
+## Num
+
+This layer gets toggled off and on to place a numpad on both the left and right sides of the keyboard.
+
+## Lower
+
+This layer holds some handy shortcuts that I use often, like the screen grab shortcut and sleep shortcut in OS X.
+
+It also has quick access to {} as they are inaccessible in the base layer
+
+## Raise
+
+Aside from quick access to [] and Play/Pause/Next/Previous, this layer is mostly just goofy things I decided to program into the keyboard because I could. There's a bunch of [kaomoji](https://en.wikipedia.org/wiki/Emoticon#Japanese_style_(kaomoji))/"unicode smileys" and I added a toggle switch to enable a [Zalgo Text](https://zalgo.org/) mode.
+
+## Adjust
+
+This layer is a "here be dragons" layer. It can only be accessed by holding down the keys for Lower and Raise at the same time. I added exclusively keys that drastically transformed the keyboard's layout or function on this layer. The ability to switch to Qwerty is on this layer, a way to switch CTRL and CMD back and forth is on this layer, and a hotkey to enter bootloader mode also exists.