macro: Apply macro_sequence_timeout within key sequences (#485)

Presently macro_sequence_timeout is strictly an inter-sequence timeout
which does not admit a pause between intra-sequence modifiers. This
patch applies such a pause to accommodate broken input stacks.

src/macro.c

@@ -139,6 +139,9 @@ void macro_execute(void (*output)(uint8_t, uint8_t),
 					output(code, 1);
 			}
 
+			if (mods && timeout)
+				usleep(timeout);
+
 			output(code, 1);
 			output(code, 0);