Android: Enforce minimum SDK version
Gradle: Force link OpenSL classes

Fixes #866
Changed SDK check per comments
Added methods to build arrow and grid models
Fixed ColorPacked bug of MeshBuilder
Use TimeUtils for GWT.
toString
Added color(Color).
Merge branch 'origin/master'
toArray without allocation.
Added functions to generate temporary matrices
Fix to keep user transform
Merge pull request #1526 from Unkn0wn0ne/patch-2

iOS: Force linked OpenSL classes
Merge pull request #1547 from lordjone/models

MeshBuilder fixes and additions
Merge pull request #1524 from Unkn0wn0ne/master

Enforced minimum SDK version on Android
Add missing methods

Fixes #1551
Fix for Music (isPlaying when paused) on iOS
Merge pull request #1552 from obigu/master

Fix for Music (isPlaying when paused) on iOS