Fix GwtGraphics.getDensity()

Previous commit changed to a double, which caused a type mismatch with the return type. 
Change HttpParametersUtils emulation.

Instead of emulating HttpParametersUtils, emulate java.net.URLEncoder.
This allows the encoding to be set (amongst the limited options available
in GWT) and provides consistency across backends.
Close writer.
Fire change event in setItems.
Remove obsolete setWidget call.
Detected usage of nested iterator() and throw exception.
Merge remote-tracking branch 'origin/master'
Issue #1353, internal getters and setters.

Getters/setters were used internally for x, y, width, height, scalex, scaley and rotation to facilitate notification when those properties are retrieved or set. Turns out overriding these isn't really very useful, so we decided not to use the getters and setters internally. Other properties that might be useful to override were left alone, such as isVisible, setStage, setParent, etc.

Also, think of all zee performancez gained!
http://youtu.be/Ay9BWM8lwOA
#1357, fixed table getRow();
#1290, native libs with applets.
Merge remote-tracking branch 'remotes/upstream/master'
Fix some conflict