#138: [1.4] childClip inside childClip does not work correctly

Originally if you had a childClip="true" element in another
childClip="true" element the clipping rectangle of the child was ignored
and the first encountered clipping rectangle (childClip="true" element)
was used.

This has now been changed and the following cases are handled:

1. If the clipping rectangle of the child element is completely outside
of its parent clipping rectangle then the clipping rectangle is not
changed.

2. Is the child clipping rectangle completely inside its parent clipping
rectangle then the child clipping rectangle will be used as the new
clipping rectangle.

3. If both rectangles intersect each other the interesection rectangle
will be calculated and used.
Merge branch '1.4' of git@github.com:void256/nifty-gui.git into 1.4
#138: Fixed new clipping rectangle intersection code

The original commit did not respect the global offset x, y values in all
cases which lead to clipping not working correctly in some cases.
#137: removed unused params from Controller interface (breaks 1.3 API!)

The parameter "controlDefinitionAttributes" in the bind() and init()
methods of the Controller interface was not really used since the same
information was available in the "parameter" parameter. Therefore the
"controlDefinitionAttributes" parameter has now been removed.

Unfortunately this change will break backwards compatibility with the
1.3 API. Your own custom controls have to be changed to the new method
signatures now.

Since the remaining parameter: "parameter" used a java.util.Properties
instance it would allow changing values which was confusing as well.
Therefore it has been changed to a dedicated instance:
"de.lessvoid.nifty.controls.Parameters" provides access to the control
parameters in a similar way but will provide only methods to get values
(and not set them). Much cleaner that way - but unfortunately is not
compatible with 1.3 as well.

Migration guide for 1.3 users:

de.lessvoid.nifty.controls.Controller Interface has been changed.

old:

* void bind(Nifty nifty, Screen screen, Element element, Properties
parameter, Attributes controlDefinitionAttributes);
* void init(Properties parameter, Attributes
controlDefinitionAttributes);

new:

* void bind(Nifty nifty, Screen screen, Element element, Parameters
parameter);
* void init(Parameters parameter);

So you have to remove the last parameter of both methods. Additionally
you have to change "Properties" into "Parameters" for the new bind()
method. If you actually used that parameter to access the control
parameters you shouldn't have to change anything else since the
Parameters class will provide the same API as Properties and Attributes
did before.
#167 Fix BatchRenderBackendCoreProfile (JOGL/LWJGL): enable GL_BLEND

Blending should be enabled for Nifty to render correctly. Usually the
RenderDevice-Implementations do that in their render() method. The new
batched render backends for core profile did not do that yet. This
commit should fix that.