Boost version update, specify filesystem v3

Shout if it breaks your favourite platform!
Avoid dynamic_cast in critcal path code.
Unused code
Remove, don't just comment out
Cache FNames to make sparse lex reorder faster
First attempt at fixing missing-backoffs bug in lmplz
eclipse
implementation of phrase orientation in GHKM extraction
(...but a corresponding feature function for the chart-based decoder has not been written yet)
Merge branch 'master' of https://github.com/moses-smt/mosesdecoder
use std::numeric_limits
merge