selectionUTest: minor bug-fix.
Added documentation
Provide extensive documentation.

The code itself is a bit opaque, so the documentation is needed.
MOSES: Updated man page.
Moses: selection scorer fixes
Moses: boosting bug fix; must rescore metapop after each weight change.
bugfix: score caching during boosting was messing up optimization.
Moses: boost debug printing fix.
moses: fix up the selection unit test
moses: fix off-by-one bug in the select unit test.
Merge pull request #962 from linas/moses-select2

Moses selection scorer implementation