Merge pull request #173 from hal3/master

minor bug fixes and code simplification
halfway through reduction restructure
Merge branch 'master' of github.com:JohnLangford/vowpal_wabbit
Merge pull request #174 from hal3/master

imperative searn short and sweet, fixed memory leaks, and tests
Merge pull request #175 from hal3/master

fast snapshotting, removed unnecssary computation
Merge branch 'master' of github.com:JohnLangford/vowpal_wabbit
new version of learner.h for easier nonuniform reduction
reductions now nonuniform
eliminated base from many places
working on neighbor features
incorporated john's changes