several improvements for mitosis:datagrok (#1960)

several improvements for mitosis:datagrok (#1960)

* mitosis/datagrok: reduce features from rules.mk

* mitosis/datagrok: make both layer keys neighbor shift

* mitosis/datagrok: (no-op) tweak some comments

* mitosis/datagrok: set baudrate to 250k

This requires a corresponding change to the mitosis wireless firmware:
https://github.com/reversebias/mitosis/pull/10

* mitosis/datagrok: move design description from code comment to a readme

* mitosis/datagrok: new layout, new shifted keys, efficient LED code

This is experimental, but compiles and seems to work correctly.

* mitosis/datagrok: whoops, move readme.md

* mitosis/datagrok: a minor layout improvement simplifies custom-shifted code

instead of [, .] [? !], using [, ?] [. !] greatly simplifies the code
needed to perform the shifted-key switching. (And keeps , and . on the
same keys that they are under qwerty.)

also: layout improvements for symbols

* mitosis/datagrok: make my code conform to QMK style guidelines

* mitosis/datagrok: TODO note for layout table in README

* mitosis/datagrok: remove led_set_user until i figure out other changes

need to see if the corresponding changes needed in the keyboard-level code
is okay.

* mitosis/datagrok: simpler layer indicator

* mitosis/datagrok: undo change to keyboard baud; make it in my layout dir.

* mitosis/datagrok: apply same punctuation hack to qwerty layer

* mitosis/datagrok: enable qwerty layer toggle

* mitosis/datagrok: update readme