Make the ErgoDox symbol available

The global `ErgoDox` symbol should be a shortcut, an alias, to KeyboardHardware.
When using ErgoDox-specific functionality, `ErgoDox.someMethod()` is much
clearer about that than `KeyboardHardware.someMethod()` would be.

Signed-off-by: Gergely Nagy <algernon@keyboard.io>

src/kaleidoscope/hardware/ErgoDox.cpp

@@ -108,3 +108,4 @@ bool ErgoDox::isKeyMasked(byte row, byte col) {
 }
 
 HARDWARE_IMPLEMENTATION KeyboardHardware;
+kaleidoscope::hardware::ErgoDox &ErgoDox = KeyboardHardware;

src/kaleidoscope/hardware/ErgoDox.h

@@ -118,3 +118,5 @@ class ErgoDox {
 
 }
 }
+
+extern kaleidoscope::hardware::ErgoDox &ErgoDox;