add even split option for classifier CV (issue #44)
(issue #46) ngram_pos_analyzer uses MeTA's CRF
make demo app for POS tagging
issue #38, filesystem::copy_file gives progress for large files
actually increment the progress counter for copy_file
appease g++
remove obsolete file
appease g++ more
clang format knn
don't show copy_file progress if it won't be used
weighted knn
skeleton for nearest_centroid
nearest_centroid classifier
unit test for nearest_centroid
Change default scores in the ranker to the largest negative number.

This is necessary e.g. for the language model rankers, where all scores
will end up negative (sum of log probabilities, which are always negative).
Use std::numeric_limits<double>::lowest() instead of min().

std::numeric_limits<double>::min() doesn't do what you would expect.
Set initial score to 0 upon finding a document matching a query term.

Fixes bug introduced in previous commit.
Merge branch 'develop' into knn
use std::numeric_limits<double>::lowest() instead of min()
Fix bugs in the formulation for the language model ranker (issue #50).

With this change, the unit test for absolute discounting in ranker_test is
now passing, so it has been added back to the test suite.