add Device:hasKeyboard to help initialize UI components

So that kindle4 won't have all the gesture event registered.

frontend/ui/device.lua

@@ -1,6 +1,7 @@
 Device = {
 	screen_saver_mode = false,
 	charging_mode = false,
+	model = nil,
 }
 
 function Device:getModel()
@@ -65,9 +66,18 @@ function Device:isKindle2()
 	end
 end
 
+function Device:hasNoKeyboard()
+	if not self.model then
+		self.model = self:getModel()
+	end
+	return self:isTouchDevice() or (self.model == "Kindle4")
+end
+
 function Device:isTouchDevice()
-	local model = self:getModel()
+	if not self.model then
-	return (model == "Kindle4") or (model == "KindlePaperWhite") or (model == "KindleTouch") or util.isEmulated()
+		self.model = self:getModel()
+	end
+	return (self.model == "KindlePaperWhite") or (self.model == "KindleTouch") or util.isEmulated()
 end
 
 function Device:intoScreenSaver()

reader.lua

@@ -62,9 +62,6 @@ end
 
 -- option parsing:
 longopts = {
-	password = "p",
-	goto = "g",
-	gamma = "G",
 	debug = "d",
 	help = "h",
 }
@@ -97,7 +94,7 @@ else
 	DEBUG = function() end
 end
 
-if Device.isKindle4() or Device:isTouchDevice() then
+if Device:hasNoKeyboard() then
 	-- remove menu item shortcut for K4
 	Menu.is_enable_shortcut = false
 end