Implement keycode set independence

This commit uses the XKB rules set passed by xrdp to set up
the keyboard mappings. This allows the dependency on the evdev
or base keycode set to be removed from xorgxrdp, and passed to
xrdp.

Some other tidy-ups, mainly around the removal of magic numbers
have been implemented.

module/rdp.h

@@ -130,14 +130,24 @@ typedef struct _rdpPointer rdpPointer;
 
 struct _rdpKeyboard
 {
-    int pause_spe;
-    int ctrl_down;
-    int alt_down;
-    int shift_down;
+    /**
+     * State of tab key
+     *
+     * Used to remove mstsc.exe tab KeyRelease before and after TS_SYNC_EVENT
+     */
     int tab_down;
-    /* this is toggled every time num lock key is released, not like the
-       above *_down vars */
-    int scroll_lock_down;
+
+    /**
+     * Whether or not to skip the next numlock key press/release
+     */
+    int skip_numlock;
+
+    int x11_keycode_caps_lock; ///< Used in TS_SYNC_EVENT processing
+    int x11_keycode_num_lock; ///< Used in TS_SYNC_EVENT processing
+    int x11_keycode_scroll_lock; ///< Used in TS_SYNC_EVENT processing
+
+    int scroll_lock_down; ///< Whether key is up/down
+    int scroll_lock_state; ///< Toggle state
     DeviceIntPtr device;
 };
 typedef struct _rdpKeyboard rdpKeyboard;