Calculate region center function modified to divide a rectangle in half
and return the center Point2f of it.
Added Google unit testing framework along with necessary folders and modifications of Makefile
Moved perceptual text grouping functions into their own namespace perceptual_text_grouping
Modified calculate_region_center to work with Rect of float point type and wrote
a test case for the calculate_region_center function
Merge branches 'perceptual_text_grouping' and 'gtest' into perceptual_text_grouping