file reorganisation

all lua frontend files are now in the frontend/ directory.
all old code is cleaned up.

frontend/ui/reader/readerrotation.lua

@@ -0,0 +1,16 @@
+ReaderRotation = InputContainer:new{
+	key_events = {
+		-- these will all generate the same event, just with different arguments
+		RotateLeft = { {"J"}, doc = "rotate left by 90 degrees", event = "Rotate", args = -90 },
+		RotateRight = { {"K"}, doc = "rotate right by 90 degrees", event = "Rotate", args = 90 },
+	},
+	current_rotation = 0
+}
+
+-- TODO: reset rotation on new document, maybe on new page?
+
+function ReaderRotation:onRotate(rotate_by)
+	self.current_rotation = (self.current_rotation + rotate_by) % 360
+	self.ui:handleEvent(Event:new("RotationUpdate", self.current_rotation))
+	return true
+end