Changed checkbox tick element from image to panel

 - The #select element actually does not show a image at all because
   the tick image is displayed using a image overlay effect that does
   not require a image element
 - The image element without filename causes a warning to be displayed
Fixed typo in IDs of scrollpanel
Changed logging of render image applying

 - There is no logging message anymore in case a image tag lacks the
   filename attribute. Reporting this seemed like a good idea at
   first, how ever in case the image tags are used to dynamically
   display a image, this message is not useful and spams the output.
 - There is a logging message now in case there is a filename
   attribute but the image loader fails to fetch a image assigned to
   this filename. In case this happens its very likely that something
   is wrong with the resources or the filename is wrong.
Marked the root of all evil.

 - The executeEndOfFrameElementActions has the potential to cause
   massive problems in case its used at any point but at the end of a
   frame. Its messes the binding and initialization process of the
   components up. This function is bad news and now everyone is told
   so.
Improved scroll panel

 - Improved access performance for scroll bars
 - Removed the nasty execute end-of-frame element actions call
Improved HTML generator

 - Removed requirement for the execute end-of-frame element action
   function
Improved list box

 - Avoided use of the execute end of frame element effects function
 - Cached element references for faster resolving
Fixed invalid null check in draggable control
Merge pull request #179 from mkaring/1.4

Some improvements of errors revealed after the refactoring