fixing bug/adding function for sticky key behavior - kbfun_press_release_preserve_sticky()

kbfun_press_release_preserve_sticky() is meant to replace
kbfun_press_release as the function used for standard modifiers (shift,
control, alt, and gui) so that the sticky state is preserved and it is
possible to key in chorded commands using a key on another layer
pressing the keys in the chord one key at a time simultaneously without
breaking the sticky state. (e.g. ctrl+F2 as lsticky2, ctrl, x [where x
is defined as F2 on layer 2]

TODO: Noticed a bug where the transparent behavior does not work as
expected for modifiers. lsticky2, ctrl, x does not produce ctrl+F2 when
ctrl is defined as transparent on layer 2 and keycode=ctrl,
press=kprrel, release=kprrel on layer 0.

src/lib/key-functions/public.h

@@ -17,6 +17,7 @@
 
 	// basic
 	void kbfun_press_release (void);
+	void kbfun_press_release_preserve_sticky (void);
 	void kbfun_toggle        (void);
 	void kbfun_transparent   (void);
 	// --- layer push/pop functions

src/lib/key-functions/public/basic.c

@@ -36,12 +36,31 @@
  *   Generate a normal keypress or keyrelease
  */
 void kbfun_press_release(void) {
-	uint8_t keycode = kb_layout_get(LAYER, ROW, COL);
 	if (!main_arg_trans_key_pressed)
 		main_arg_any_non_trans_key_pressed = true;
+	kbfun_press_release_preserve_sticky();
+}
+//TODO: 
+
+/*
+ * [name]
+ *   Press|Release and preserve top layer sticky key state
+ *
+ * [description]
+ *   Generate a normal keypress or keyrelease
+ *   While basing the sticky key state transition on whether
+ *    kbfun_press_release() was called after kbfun_transparent() generally
+ *    works in practice, it is not always the desired behavior. One of the
+ *    benefits of sticky keys is avoiding key chording, so we want to make sure
+ *    that standard modifiers do not interrupt the sticky key cycle. Use
+ *    kbfun_press_release_preserve_sticky() if you want to define a standard
+ *    modifier key (shift, control, alt, gui) on the sticky layer instead of
+ *    defining the key to be transparent for the layer.
+ */
+void kbfun_press_release_preserve_sticky(void) {
+	uint8_t keycode = kb_layout_get(LAYER, ROW, COL);
 	_kbfun_press_release(IS_PRESSED, keycode);
 }
-
 /*
  * [name]
  *   Toggle