Primitive text direction feature detector

v.1.1 of text direction feature detector :)
Suppose len(sections) = 5, i=1, group_section_below_threshold(sections[i]) = True.
You collapse sections[0], sections[1], sections[2] into new sections[0]. Old sections[3] becomes new sections[1]. On next iteration i=2, you move on to new sections[2], skipping new sections[1]. 
Though this is going to be reiterated and caught up on later 'while' iteration, this seems to be unnecessary skipping.