Line descriptor module

This module has been designed for Google's GSoc 2014.
It contains functionalities for:
- extraction of lines from an image
- definition of a new class KeyLine for representing lines
- representation of lines through descriptors
- new binary descriptors matcher based on MiHasher

A part of documentation is included.
do you mean std::vector<uint32_t> or std::valarray<uint32_t> in place of class Array32?