Fixed Bug: loopDuration could be wrong

The loopDuration could be higher than the sum of all durations when the
float had more than 3 decimal places.
Implement pan/pitch/volume/loop
Use int for animationInterval instead of long

With an integer a loopDuration of 24 days is possible which is more
than enough. Long is unnecessary big.
Remove posted runnables as they are run.

If `executeRunnables()` is called from a posted runnable, this commit prevents the runnable from being executed twice.
Add getTextInput accepting both text and hint values
Remove old getTextInput and getPlaceholderTextInput
Improved limit()/clamp() behaviour - now it doesn't call nor(), reusing the
(needed anyway) len var, resulting in *one* scl() call instead of *two*.
Also, we use cached len, so that we don't have to calculate it twice.
Mostly beneficial for Vector3 class.
Also adds limit2(),setLength(), setLength2() and removes docs inherited
from Vector interface
added missing methods to GWT WeldJoint

and fixed getFrequency()
Merge pull request #2571 from dermetfan/patch-1

added missing methods to GWT WeldJoint
added missing setMaxLength(..) to GWT RopeJoint
Merge pull request #2572 from dermetfan/patch-1

added missing setMaxLength(..) to GWT RopeJoint
Merge pull request #2544 from vaxquis/master

Improved limit()/clamp() behaviour - now it doesn't call nor(), reusing ...
Merge remote-tracking branch 'origin/master'
Missing exception text.
Fixed TexturePacker.Settings copy constructor.
Y u alwayz commit warnings?!
 Fixes missing keycodes, cleans up & sorts existing ones.

 An essential/prerequisite commit for further Input improvements, e.g. #2524
Merge branch 'master' of https://github.com/libgdx/libgdx

Conflicts:
	gdx/src/com/badlogic/gdx/Input.java
Fixed button visual press time.

Jamming a long into a float is not good.
Fixed scene2d.ui widgets for noncontinuous rendering. Other clean up.

closes #2583
closes #2582
#2229