keybinds: add support for Meta and Hyper modifiers

The modifiers can be used in keybinds via M-key and H-key

Additionally adds support for:
- Mod1 (same as A)
- Mod3 (same as H)
- Mod4 (same as W)
- Mod5 (same as M)

This is compatible with the format used by Openbox.
(http://openbox.org/wiki/Help:Bindings#Syntax)

Mod2 (NumLock) and Caps are still not supported due to
their locking behavior but could theoretically be added.

Fixes: #1061

src/config/keybind.c

@@ -15,14 +15,19 @@
 uint32_t
 parse_modifier(const char *symname)
 {
+	/* Mod2 == NumLock */
 	if (!strcmp(symname, "S")) {
 		return WLR_MODIFIER_SHIFT;
 	} else if (!strcmp(symname, "C")) {
 		return WLR_MODIFIER_CTRL;
-	} else if (!strcmp(symname, "A")) {
+	} else if (!strcmp(symname, "A") || !strcmp(symname, "Mod1")) {
 		return WLR_MODIFIER_ALT;
-	} else if (!strcmp(symname, "W")) {
+	} else if (!strcmp(symname, "W") || !strcmp(symname, "Mod4")) {
 		return WLR_MODIFIER_LOGO;
+	} else if (!strcmp(symname, "M") || !strcmp(symname, "Mod5")) {
+		return WLR_MODIFIER_MOD5;
+	} else if (!strcmp(symname, "H") || !strcmp(symname, "Mod3")) {
+		return WLR_MODIFIER_MOD3;
 	} else {
 		return 0;
 	}

src/keyboard.c

@@ -130,7 +130,10 @@ static bool is_modifier_key(xkb_keysym_t sym)
 		|| sym == XKB_KEY_Control_L
 		|| sym == XKB_KEY_Control_R
 		|| sym == XKB_KEY_Super_L
-		|| sym == XKB_KEY_Super_R;
+		|| sym == XKB_KEY_Super_R
+		/* Right hand Alt key for Mod5 */
+		|| sym == XKB_KEY_Mode_switch
+		|| sym == XKB_KEY_ISO_Level3_Shift;
 }
 
 struct keysyms {