PERF: Changing filters to use ImageScanlineInterator

The ImageScanlineIterator offers a more optimized inner loop, and
performance improvements. Basic usage of ImageRegionIterator in
several easy filters has been replaced with the ImageScanlineIterator.

Minor loop restructuring to the double while loop was performed from
some for loops.

Some GoToBegin() calls were removed as they are not needed after an
iterator constructor.

Change-Id: Iad890e6d721973c4c9c260f4be4e2888dbe932c0
Merge topic 'UseImageScanlineIterator'

e179cec PERF: Changing filters to use ImageScanlineInterator