Merge pull request #23 from tinnet/master

added 2 and 3 dimensional array allocation/creation functions
add DrawImageRect() to Sprite
fix rendering of scales graphics.Sprite
fix scaled graphics.Sprite in graphics.Align
always handle failed LoadImage() in Sprite
allow active Keyemitter with hidden keyboard
add ArrayHelper<T>.RandomChoice:T(T[])
fix 3-dimension ArrayHelper<T>.CreateArray()
fix compile error in StringHelper.Randomize()
add StringHelper.Join() for Int and Float
tests for StringHelper and ArrayHelper
reduce output of TestReportSimple if verbose=False
get tests running with TARGET=html5