restructure converters (#1825)

* restructure converters

each converter is its own keyboard and different hardware variants are different subprojects.

remove (seemingly) old method of loading layouts from main Makefile

* call led_set_kb() from overridden led_set()

* put converter back into one folder

* revert some structure changes to bring in line with #1784.

Also attempt to get the BLE thing more properly integrated.
Also also fix led_set() to call led_set_kb().

keyboards/converter/usb_usb/README.md

@@ -13,13 +13,18 @@ Make example for this keyboard (after setting up your build environment):
 
 See [build environment setup](https://docs.qmk.fm/build_environment_setup.html) then the [make instructions](https://docs.qmk.fm/make_instructions.html) for more information.
 
+Note that you have to choose the right hardware variant as your subproject, otherwise you will probably have issues.
+
 Troubleshooting & Known Issues
 ------------------------------
-The Pro Micro variant runs at 8MHz, hence the following line in `usb_usb/rules.mk`:
-`F_CPU ?= 8000000`
-If the firmware doesn't work, try changing that line to
-`F_CPU ?= 16000000`
-or override the `F_CPU` variable in the `rules.mk` of your keymap.
+If something doesn't work, it's probably because of the CPU clock. 
+Be sure to select the correct subproject (the middle part of the `make` argument) according to your hardware. 
+If you are sure you have this correct, try changeing the default in `usb_usb/rules.mk` or overriding the value in the `rules.mk` of your keymap.
+
+The Pro Micro variant uses a 3.3V Pro Micro and thus runs at 8MHz, hence the following line in `usb_usb/pro_micro/rules.mk`:
+`F_CPU = 8000000`
+The converter sold by Hasu runs at 16MHz and so the corresponding line in `usb_usb/hasu/rules.mk` is:
+`F_CPU = 16000000`
 
 Getting the Hardware
 --------------------