Merge branch 'release/0.27.0' into develop
Loading progress now indicated by printing line numbers. Fixes #93
Sanitize .libsvm class/feature names before we print them.
Fix some bugs with loading libsvm files
Add missing | replacement to LIBSVM_REPLACE_DICT
Started refactoring data.py into a subpackage.

- Have very preliminary version of FeatureSet class.
- DictIters were moved into data.readers
- write_feature_file functions were moved into data.writers

Probably need to come up with a better name than DictIter for readers.
Add skeleton of filter and subtraction FeatureSet methods
Clean up imports in featureset.py
Fixes #144
Add initial version of FeatureSet class
Refactor data module into featureset, readers, and writers modules.

The main idea here was that I wanted to make it easier for us to write
utilities that manipulate feature sets.  I've updated skll_convert to
use the new Readers and Writers, but I should also be able to replace
join_megam and filter_megam with more generic join_feature_set and
filter_feature_set tools.

This is not entirely done yet, because I still need to refactor
the experiments module to use all of this stuff.
Revert accidentally committed changes to Titanic example.
Merge branch 'develop' of github.com:EducationalTestingService/skll into develop
Merge branch 'develop' into feature/create_featureset_class
Fix a lot of remaining issues with FeatureSet.
Finish refactoring readers module.

It wasn't actually done before. It's also quite a bit simpler now. We
only use one subprocess for reading in files. I don't think this should
really impact speed much though, because only the DictVectorizer
building is very slow.
Fix issue where fieldnames wasn't being returned by _get_fieldnames
fix issue where dictvectorizer wasn't being updated properly in FeatureSet.__add__
Update Travis settings to run nose in verbose mode.
Create separate TSVWriter and CSVWriter subclasses.