best constant for all loss functions
add best_constant.cc to build chain
align tests output with new best constant algorithm
best constant output disabeled for unsupported vw modes
"squaredloss" -> "squared"
"current features" include all lines of an ldf example

Number of current features (reported in the last column of vw progress) should include all features of multiline csoaa_ldf examples.
getting uniq labels count to filter best constant output
"current features" include also "shared" features in ldf examples

Number of current features (reported in the last column of vw progress)
should be the same no matter if we use "shared" features or manually copy those features to each line.
TODO: this still doesn't work with --quadratic and --cubic
beacuse VW::setup_example is called before the namespaces from "shared" are added via add_example_namespaces_from_example.
FLT_MAX fix for Travis CI
Better handling and error message on time-out.
RunTests: better handling of missing commands + clearer error message
Merge pull request #449 from arielf/master

Better error handling and messages in RunTests (timeout and non-existent commands)
Merge pull request #445 from trufanov-nok/master

best constant for all loss functions
Merge pull request #448 from martinpopel/issue439

reported number of "current features" for ldf examples
changing labels is all good