ipc: share one keysym and modifier mapping across frontends

The keysym-to-engine-key rule lived in ibus.c, xim/xim.c and gtk/main.c,
and the copies disagreed: GTK sent keypad digits as special keys while
IBus and XIM sent '1'..'9'. Modifiers were rebuilt bit by bit in two
places although Mmask already is the X core layout; only the virtual
Super bit (26) that GDK and IBus set needs folding. ipckey/ipcmod in
ipc.c serve the daemon, the module and the tests.

xim/xim.c

@@ -249,12 +249,6 @@ out:
 	return ok;
 }
 
-static u32int
-kget(uint8_t kc, u16int state)
-{
-	return keymaplookup(kstate, kc, state);
-}
-
 static xcb_screen_t*
 getscreen(int scr)
 {
@@ -466,7 +460,7 @@ sendrequest(Ic *state, int op, u32int key, u32int mod, Keyres *res)
 	kr.cap = state->cap;
 	kr.op = op;
 	kr.ks = key;
-	kr.mod = mod & Mmask;
+	kr.mod = ipcmod(mod);
 	kr.caret = state->caret;
 	kr.reply = replyc;
 	chansend(keyc, &kr);
@@ -557,17 +551,11 @@ kpress(Ic *state, xcb_key_press_event_t *ev)
 {
 	Keyres res;
 	char buf[Maxutf];
-	u32int key, rune;
+	u32int key;
 	int n, wasvalid;
 
-	key = kget(ev->detail, ev->state);
-	rune = xkb_keysym_to_utf32(key);
-	if(rune >= ' ' && rune != 0x7f)
-		key = rune;
-	else if(key >= 0xff00 && key <= 0xffff)
-		key = Kspec + (key - 0xff00);
-	else
-		key = rune;
+	key = keymaplookup(kstate, ev->detail, ev->state);
+	key = ipckey(key, xkb_keysym_to_utf32(key));
 	if(meaningful(key)){
 		wasvalid = state->caret.valid;
 		refreshplace(state);