`rppr infer` infers conservative classifications for unclassified reference package sequences

[matsen]

Given a reference package such that some sequences are unclassified, spit out a complete CSV seq info file with taxonomic annotations for the unclasified ones. These classifications should be conservative!

Steps include

• cutting the unclassified reference sequences out of the ref tree
• placing and classifying (for a conservative classification, take the most specific classification that contains 100% of the mass)
• spitting out the classifications

First step is writing a test first for the tree surgery. In the case of an entirely unclassified subtree, it will all want to get taken out (an MRCA approach would be useful here).

[matsen]

Let's work together on Tuesday to merge these in.

"Details" documentation for this and reclass seem missing. Dev needs to get merged in-- there was a conflict.