Add derivative calculations to CatmullRomSpline

I added the calculation of the derivative of the spline. This finds the tangent of the curve at the desired point.
Added Function getRemoteAddress() for Socket so it´s possible to implement reconnection logic or peer to peer networking
Add Matrix4#setTranslation(float, float, float)
Frustum: add methods using floats instead of Vector3
Stringbuilder: add minimum length for int/long
Made libgdx version configurable in gdx-setup
Only move window within title bounds.

Modal windows capture all touchd owns.
Clean up stream handling
Merge pull request #948 from hneuer/streams

Clean up stream handling
Javadoc

closes #949
Merge branch 'origin/master'
Added Immersive Mode option
Set skin on dialog table.
Added Android 4.4 Kitkat Immersive Support
Fixed accidental typos, sorry.
Added Actual Immersive Mode
Updated Android library to Android 4.4 for Immersive Mode

Immersive Mode needs a flag that requires the Android 4.4 libraries
Add setX and setY to TextureAtlas.AtlasSprite so that it matches expected whitespace behavior.
Path interface now has the method derivativeAt()

Path interface now has the method derivativeAt() that calculates the tangent of the curve at the desired point.
Added derivatives, commentaries with expanded formula

Added derivative calculation to linear, quadratic and cubic curves.
Added commentary to explain the curve and derivative formulas