Table package improvements

[Andrew Janke]

Hi, folks, and especially jwe,

I've made some progress with my nascent table package. I've added:

  * @string and @categorical classes
  * Missing Data support
  * @datetime support (by merging in my Chrono package)
  * Documentation
  * Documentation tooling support for mult-part Texinfo in classdef files
  * Example data sets (not many, but a few, and a framework for using them)
  * Most of the rest of the basic @table functionality

I'd say it's still only about 50% complete, but the basics are pretty
much there, and it's good enough to test and use for some interactive
analysis. I've also renamed it to "Tablicious".

If you'd like to have a look at it, it's here:
Documentation:
https://apjanke.github.io/octave-tablicious/doc/tablicious.html
Code: https://github.com/apjanke/octave-tablicious
Issues and project plan: https://github.com/users/apjanke/projects/1

The documentation is now good enough that it ought to be a good starting
point. If you have any questions that aren't answered by the doco, let
me know, and I'll add to it!

Cheers,
Andrew