terminal: don't use env variable to give a name to GTK terminal

GTK applications accept `--name` as a special parameter just for that.

rc/quake.lua

@@ -3,7 +3,7 @@ local quake = loadrc("quake", "vbe/quake")
 local quakeconsole = {}
 for s = 1, screen.count() do
    quakeconsole[s] = quake({ terminal = config.terminal,
-                             argname = " ",
+                             argname = "--name %s",
 			     height = 0.3,
 			     screen = s })
 end