Fix issue with forward_index uninversion creation with empty documents.

Empty documents do not appear in the postings file for the inverted_index,
so they need to be treated specially in the uninversion process.
Add a warning if a document tokenizes to an empty document in indexing.

This can happen if a document contains only words that are filtered out by
the chosen filter chain.
add exception when inverted and forward indexes are the same
Merge branch 'develop' of ssh://github.com/meta-toolkit/meta into develop
make label ids start from one for compatibility with svm light
make the parser split on delimiters instead of consuming them
Fix libsvm_parser tests.
give default config file all valid options and no commented out sections
Merge branch 'develop' of ssh://github.com/meta-toolkit/meta into develop
Fix CVB0 inference for lda, add sanity checking to output of the model.
Merge branch 'develop' of github.com:meta-toolkit/meta into develop
dual license
update license info in header files
Remove accidental leftover comment in lda_cvb.
Add implementation of SCVB0.
Merge branch 'develop' into sequence
Minor work on feature generation for sequence data for POS tagger.