v0.3.2 Release

Cutting 0.3.2 release in conjunction with submission of scikit-spectra publication to the Journal of Open Research Software. PyPi also updated so these should all correspond. At this point in development, documenation is still on gh-pages branch rather than in the main repo, so could be some disconnect between documentation and this release in terms of updates. In future versions, docs will also be released in the same branch as the version.