[algorithm] [searching] Add longest increasing substring algorithm.
[algorithm] [searching] [longest_increasing_substring] Add more tests. Fix. Clean. Doc.
Format. Add .clang-format (needs current development version of clang-format ~3.6).
Merge branch 'feature/longest-increasing-substring' of https://github.com/MarekKurdej/algorithm into feature/longest-increasing-substring

Conflicts:
	include/boost/algorithm/searching/longest_increasing_substring.hpp
	test/Jamfile.v2
	test/substring_test1.cpp