Add textedited callback

Author: rm-code

Screen.lua

@@ -77,6 +77,8 @@ function Screen.new()
 
     function self:resize() end
 
+    function self:textedited() end
+    
     function self:textinput() end
 
     function self:touchmoved() end

ScreenManager.lua

@@ -258,6 +258,17 @@ function ScreenManager.resize( w, h )
     end
 end
 
+---
+-- Called when the candidate text for an IME (Input Method Editor) has changed.
+-- The candidate text is not the final text that the user will eventually choose. Use love.textinput for that.
+-- @param text - The UTF-8 encoded unicode candidate text.
+-- @param start - The start cursor of the selected candidate text.
+-- @param length - The length of the selected candidate text. May be 0.
+--
+function ScreenManager.textedited( text, start, length )
+    ScreenManager.peek():textedited( text, start, length );
+end
+
 ---
 -- Reroute the textinput callback to the currently active screen.
 -- @param input