Implement OneShot.isPressed()

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

README.md

@@ -102,6 +102,10 @@ modifiers and one-shot layer keys. It has the following methods:
 > useful for macros that need to fiddle with either modifier or layer state: if
 > one-shots are not active, they need not restore the original state.
 
+### `.isPressed()`
+
+> Returns true if any one-shot key is still held.
+
 ### `.isSticky(key)`
 
 > Returns if the key is currently sticky.

src/Kaleidoscope/OneShot.h

@@ -34,6 +34,9 @@ class OneShot : public kaleidoscope::Plugin {
     return (key.raw >= kaleidoscope::ranges::OS_FIRST && key.raw <= kaleidoscope::ranges::OS_LAST);
   }
   static bool isActive(void);
+  static bool isPressed() {
+    return !!pressed_state_.all;
+  }
   static bool isActive(Key key);
   static bool isSticky(Key key);
   static void cancel(bool with_stickies);