Add links to grammar pages to altlab.tsv

[aarppe]

At some point, we'd want to be able to link linguistic features, whether resulting form the FST analysis of a word-form or from the lexical database (e.g. inflectional categories) to related grammar pages, e.g. the ones available here.

For this purpose, we should add an additional column to altlab.tsv for including these links. The links can be shared across multiple features.

[aarppe]

Added 7th column for including links, when available and appropriate, with commit f6624b1.

[aarppe]

Added links to the four major parts-of-speech (N: noun, V: verb, Pron: pronoun, and Ipc: particle), with commit: b5b2480

@Eluviian This would mean that one could prototype opening a link, when clicking on a relabelled feature in a pop-up, e.g. N in the following analysis, where the underlying labelling is: +N+A+Sg.

This linking should work from the linguistic analysis information button, the inflectional class field, and (eventually) from the column and row labels in the paradigm panes, cf.