[hbck] Add region coverage visualization to hbck

After HBASE-4322 and HBASE-4321, we now have an accurate region splits / coverage map for properly identifying holes, overlaps, backwards regions and other kinds of problems in the .META. table. hbck should display this information so that someone can fix this.

A simple version for a table with regions [,A], [A,B], [A,C], [C,] and would dump out something like this (showing an overlap in [A,B])

: ['table,,..', 'table,A,..']
A: ['table,A,..', 'B'] ['table,A,..', 'C']
B: ['table,A,..', 'C']
C: ['table,C', '']
null:

My first thought is '-details' should this dump the full region map including all good and bad regions. Without -details, any errors should dump info with some context – dump one region before problems, problem regions, and then one post problem region.

Alternately we could add a new option or options to dump the region split map.

What is the preferred way to toggle display of this information in hbck?