Creates a layouts/ folder for keymaps shared between keyboards (#1609)

* include variables and .h files as pp directives

* start layout compilation

* split ergodoxes up

* don't compile all layouts for everything

* might seg fault

* reset layouts variable

* actually reset layouts

* include rules.mk instead

* remove includes from rules.mk

* update variable setting

* load visualizer from path

* adds some more examples

* adds more layouts

* more boards added

* more boards added

* adds documentation for layouts

* use lowercase names for LAYOUT_

* add layout.json files for each layout

* add community folder, default keymaps for layouts

* touch-up default layouts

* touch-up layouts, some keyboard rules.mk

* update documentation for layouts

* fix up serial/i2c switches

1 files changed, 32 insertions, 0 deletions

diff --git a/layouts/community/ergodox/j3rn/readme.md b/layouts/community/ergodox/j3rn/readme.md
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+# J3RN's Mac-Centric ErgoDox EZ keymap
+
+## Motivation
+
+Essentially, I wanted to switch to a layout that was less jarring than the default ErgoDox EZ layout, and did not require finger gymnastics to perform common OS X shortcuts (most of which involve the CMD (LGui) key).
+
+## How is it different from the default ErgoDox EZ layout?
+
+This layout more closely resembles that of the Mac keyboard, and has some other goodness baked in. Here is a rundown of what that means:
+
+### Mac-like changes
+
+- **The key to the left of "1" is "~" instead of "=".**
+- **The key to the right of "0" is Backspace instead of "-"** (misleadingly labeled "delete" on the Mac's keyboard). There was no room to fit in "-" and "=" between "0" and Backspace, unfortunately.
+- **The key to the left of "Q" is Tab instead of Delete.**
+- **The rightmost big key on the left thumb is CMD (LGui) instead of Backspace.**
+- **The key to the left of Alt-Shift is an Alt key**. This is close to it's position on the Mac keyboard, though slightly further left.
+
+### Other changes
+
+- **The button to the left of "A" is Ctrl/Esc instead of Backspace.** This is actually how I have the keyboard on my Macbook set up to be, since it's loads more convenient than a  CAPS LOCK key. This is the Ctrl key I find myself using most.
+- **Mouse uses Vim-style navigation**. To activate "Media mode," hold the 'a' key. This allows you to move the mouse around with hjkl just like in Vim. Additionally, right and left click are the conveniently placed 'i' and 'o' keys.
+- **The key to the right of "5" and the key to left of "6" are "[" and "]", respectively, instead of Left and Right.** There is a more convenient set of Left and Right already present. Truth be told, I don't really use these keys, as they are a stretch to reach.
+- **The Toggle L1 keys have been replaced by the otherwise displaced "-" and "=".** They are laid out, left-to-right, in the same order as on the Mac keyboard. Honestly, they are not terribly conveniently placed, and their placement might change in a later version. I found that I did not toggle L1 frequently at all, and found using the momentary keys to access L1 to fit my workflow better.
+- **The "~"/L1 key in the bottom-left is now just momentary L1.** The "~" key was moved to the top-left as mentioned before, and I like to keep my multi-use keys to a minimum due to the latency for them to switch from "press" to "hold."
+- **The Home and End buttons have been shifted up on the left thumb, and Shift inserted below them.** This makes doing Shift-5 and other such combinations less painful.
+- **The Page Up and Page Down buttons have been shifted up on the right thumb.** I don't use either of these keys often, and wanted to free up some real estate.
+- **The bottommost-inner keys on the left and right thumb are momentary L2 and momentary L1, respectively**. I have found that both modes are useful, and this seemed like a reasonably accessible place to put these.
+- **Traditional numpad layout.** The base of most numpads is a double-wide "0" key to the left of a "." key. This is reflected in my layout by having two "0" keys to the left of a "." key.
+- **The function keys (F1-F12) have been moved to L2.** They were in the way in L1.
+
+**I'm always open to feedback and/or suggestions!**