Add Bluepill (stm32f103) handwired keyboard (#4126)

Add Bluepill (stm32f103) handwired keyboard (#4126)

* Main folder

Main folder with some changes like the base layout and matrix for uploading in a future to the qmk repositorie

* First Commit

Firsts non previously commited changes:
-Changed to keyboards/handwired
-Basic credit to Xydane
-70% Layout

* Modified file structure for several keyboards

As I don't want to create several folders and overcrowd the main folders I made a few modifications to being able of configure several keyboards as revisions of the main keyboard.
Added a second variant.
Compiling tests went right but I haven't tried it on the controller.

* Starting leds

* Started dual color leds PWM functions and configs

I started to create the PWM functions and configs based on internet examples, it doesn't compile yet

* Backtraced a bit to establish and try debug before continuing the pwm

Just this, algo some doc as a new pinout image, space cadet modification to try if it works and little more

* Deleted unuseful stuff

After trying the reestructure to being compatible with several keyboards and that it worked I deleted the other keyboard.
Added space cadet shift to ISO.
Finally I couldn't debug everything and I'm getting quite frustrated to continue much more than just adding pwm leds

* Changed again Iso fix for Space Cadet

* Renamed keyboard, future pull

I just renamed the keyboard and made some simplifying changes in order to make a pull request sometime soon.

I'm too frustrated, tired and knowledge limited to achive using the PWM for leds, I didn't even get to use the debug mode...

I intend to end basic led color change using layers (if I can), document everything properly and make a pull request so other users can continue/use this project.

* Writed Readme.md file

I also corrected a previous compilation problem and ordered a bit the keymaps

* Corrected readme

* Try to add layer activated light

* Revert "Try to add layer activated light"

This reverts commit 205af820d845dab08988f329b9f062f558060220.

* Progress to fork

Coming back to work, upcoming pull

* Linked image

Corrected readme

* Some cleanning

Added images to readme, som cleaning, burning after commit.

* Almost finished (working)

Finally

* Finished bluepill firmware

Just finished and tried layer dependant led colors. Going for merge

* Deleted innecesary stuff and trailing spaces

Just as commit title said.

* Coding conventions

Just modified some files to respect coding conventions

* Deleted XXXXXX define

Checking some other PR seen this improvement

* Changes suggested on PR

Firs doing the easy changes

* More changes for the PR

-I also deleted one unused function for led toggling on matrix.c (Now it uses layer dependent baklight, algo on of on start)
-Deleted commented function on keymaps.

Right now only needs testing and all pragma replaces.

* Almost every pragma change on PR

That's almost finished, only waiting for reply due to compiling errors

* Revert "Almost every pragma change on PR"

This reverts commit 07f23aa862b370cdf0ae37d6f2130c9e9856f491.

* Revert last commit

I moddified by mistake a file from another keyboard

* Solved last pragma

Compiles fine.
Now I only need to test it, I say you if it works to include it in the main repository.