QMK DFU bootloader generation (#2009)

* adds :bootloader target

* update planck and preonic revisions

* remove references to .h files for planck

* update preonic keymap

* only add keyboard.h files that exist

* add production target

* hook things up with the new lufa variables

* update rules for planck/preonic

* back backlight key turn of status led when pressed

* add manufacturer/product strings to bootloader

keyboards/planck/keymaps/default/keymap.c

@@ -224,8 +224,10 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         #ifdef BACKLIGHT_ENABLE
           backlight_step();
         #endif
+        PORTE &= ~(1<<6);
       } else {
         unregister_code(KC_RSFT);
+        PORTE |= (1<<6);
       }
       return false;
       break;