Filtering performance

[mozharovsky]

Filtering operations are being performed very slow. This is a huge problem for general app performance.

Approach

Wrappers around CIFilter hierarchy are nice. But the Processor is not well optimized which makes processing a set of images kinda problematic and time consuming. This, basically, is happening because of using a default CIContext which mainly uses the CPU. Instead we'd rather use a context using GPU for the same purpose.

Tasks

• Optimize Processor implementation
• Use GPU for processing operations (also see GPU image processing #1)
• Update the Demo project
• Update the Pod