Allow MeTA to be compiled with -std=c++14.
Merge branch 'develop' of github.com:meta-toolkit/meta into develop
Change origin for porter2_stemmer.
Add meta's include directory to the meta-definitions INTERFACE target.
Fix meta-analyzers for use in outside projects.

Something weird was going on with linking. I actually don't think we can
separate the analyzers into separate libraries anyway, so I've just
dropped that part of the modularization and things seem to be working
fine...
Fix building with travis.
Fix compilation with ICU < 4.4.

(This is basically only useful for EWS... but I want MeTA to compile there.)
Fix missing underscore.
Add sparse_vector class.

This should be useful in several places where we want to use a sorted
vector of pairs to represent either a sparse vector or a dictionary.
Begin work on stats library for meta.

This is mainly to try to make it easier to follow things when we're doing
probabilistic modeling: instead of carrying around maps of parameters, we
should be using classes to represent the distributions themselves instead.
Port naive bayes classifier to use stats models.

(I think I've fixed a bug with it in the process, as it's doing much much
better now in terms of performance.)
Fix compilation with gcc.