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/ble/README.md

@@ -0,0 +1,30 @@
+QMK BLE Adapter
+===============
+A small device that reads USB keyboard input and passes it on over Bluetooth LE HID.
+
+![Picture of Adapter](https://i.imgur.com/O3VwBBJ.png)
+
+Hardware
+--------
+The hardware is relatively easy to assemble. Just follow the schematic and don't forget to [cut the VBUS jumper](https://www.pjrc.com/teensy/td_libs_USBHostShield_4a.jpg).
+
+Schematic:
+![Schematic](https://i.imgur.com/s1Ia9We.png)
+
+Part list:
+* [Adafruit Feather 32u4 Bluefruit LE](https://www.adafruit.com/product/2829)
+* [USB Host Mini](https://www.circuitsathome.com/arduino_usb_host_shield_projects/)
+* [Pololu 5V Step-Up Voltage Regulator U3V12F5](https://www.pololu.com/product/2115)
+* [Lithium Ion Battery - 3.7v 2000mAh](https://www.adafruit.com/product/2011)
+* Some sort of switch to be able to turn it off
+
+Building and Flashing
+---------------------
+
+```
+make converter-usb_usb-ble
+```
+
+```
+make converter-usb_usb-ble-avrdude
+```

keyboards/converter/usb_usb/ble/ble.c

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+#include "ble.h"

keyboards/converter/usb_usb/ble/ble.h

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+#ifndef BLE_H
+#define BLE_H
+
+#include QMK_KEYBOARD_H
+
+#endif

keyboards/converter/usb_usb/ble/config.h

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+#ifndef CONFIG_BLE_H
+#define CONFIG_BLE_H
+
+#undef PRODUCT
+#define PRODUCT         QMK BLE Adapter
+#undef DESCRIPTION
+#define DESCRIPTION  
+
+// Turn off the mode leds on the BLE module
+#define ADAFRUIT_BLE_ENABLE_MODE_LEDS 0
+#define ADAFRUIT_BLE_ENABLE_POWER_LED 0
+
+#endif

keyboards/converter/usb_usb/ble/rules.mk

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+BLUETOOTH = AdafruitBLE
+ADAFRUIT_BLE_ENABLE = yes
+OPT_DEFS +=  -DCATERINA_BOOTLOADER
+F_CPU = 8000000