call UIGraphicsEndImageContext after img created 

Call UIGraphicsEndImageContext after cachedVisualRepresentation created, recyle graphics context, with out this line memory will leak
improved performance by adding batching to get rid of wasted draw calls.
fixed spelling error
Merge pull request #1 from zhanleewo/master

call UIGraphicsEndImageContext after img created
Merge pull request #2 from RyanBertrand/master

Added batching to reduce wasted draw calls
updating version
Merge remote-tracking branch 'upstream/master'