Made a userspace that allows you to use your keyboard as an order of operations based...

Made a userspace that allows you to use your keyboard as an order of operations based calculator (#2864)

* Made DZ60 layout with calculator

* Cleaned up and commented, preparing to fix bug with negative in front of open parenthesis as first character

* Fixed bug where negative sign infront of parenthesis as first character was parsed incorrectly

* Made a better solution for the bug from the previous commit

* Modularized and added a userfile so that this code can be used on various keyboards, found in doogle999

* Removed commented code from keymap

* Made the layer that is used for calculations a define so that it can be changed per keyboard

* Made the readme

* Made the readme in the correct place

* Revert "Made the readme in the correct place"

This reverts commit 7f8b59ed9e59c77401a48be3a7ac1e8fd8e84e32.

* Manually synced with qmk upstream

* Stopped repeat, made keys print character that they are defined as rather than what the keyboard wants them to do

* Added support for numpad, might make all keycodes custom so that there is no need to change doogle999.c if you want to change the keycode that is associated with a function, also made numpad automatically activating an option

* Fixed some bugs with backspacing, updated the readme

* Fixed some bugs with numlock turning on at the wrong times when a shift key was down

* Made the return to layer work automatically instead of just forcing it to layer 0

* fixes and style changes, 20% decreased binary size

* Fixed some bugs with double printing and compilation errors on my side

* Fixed bug with exceeding the buffer size

* Removed changes that added const-ness

* Made changes so that backspace does not repeat to remove backspace bugs, still some bugs with recalculating without having typed anything

* Fixed obo error with calc main loop

* Made includes more accurate in keymap for dz60

* Moved flags to user makefile