Rewritten event system to remove all macros, to make user code clearer.

Fixed incorrect ENDPOINT_EPNUM_MASK mask preventing endpoints above EP3 from being selected (thanks to Jonathan Oakley).

Removed STREAM_CALLBACK() macro - callbacks now use regular function definitions to clarify user code.

Removed DESCRIPTOR_COMPARATOR() macro - comparators should now use regular function definitions to clarify user code.

Demos/Host/KeyboardHostWithParser/makefile

@@ -507,7 +507,7 @@ sizeafter:
 checkhooks: build
 	@echo
 	@echo ------- Unhooked LUFA Events -------
-	@$(shell) (grep -s '^Event.*LUFA/.*\\.o' $(TARGET).map | \
+	@$(shell) (grep -s '^EVENT_.*LUFA/.*\\.o' $(TARGET).map | \
 	           cut -d' ' -f1 | cut -d'_' -f2- | grep ".*") || \
 			   echo "(None)"
 	@echo ------------------------------------