text-classify: save net, and add --filename option
text-classify: comments on the utf-8 legend generator
Add text-classify-results, to make use of text-classify nets

`text-classify` supposedly trains a net to decide the class of a text.

`text-classify-results` emits the class probabilities of texts
according to the net trained by `text-classify`.
charmodel: don't despair when alphabet length differs from net size

With text-classify, this situation is normal.
charmodel: provide more info in the case of unicode errors
charmodel: a function to find the encoding of a character

For example:

    int x = rnn_char_get_codepoint(alphabet, "\n");

will return the codepoint for '\n'.
charmodel: add option to stop on a certain character

This is useful when the start and end of documents are marked by
special tokens.
charmodel: test_backprop works with line-endings in confab

If white space is not collapsed, assume that \n is possible, and that
\n ends a line. That means the confabulation has to stop early.

Also, use colour when doing that.
charmodel: text-confabulate gains --prefix argument

This is used to prime the network with a string of characters,
hoepfully getting it into a reasonable state.
text-confabulate: --show-prefix option for printing prefix

A common informal qualitive test of language models in to begin with
the text "the meaning of life is " and see how it continues. This
makes that kind of thing slightly easier to comprehend.
text-confabulate: --wait-for option to begin output at a certain char

This is for the case where documents are marked with start and/or end
characters. Combining --wait-for and --until can capture an entire
confabulated document.
Rename test_backprop, text-predict

This is for consistency. test_backprop began as a test.
text exes: include opt.h through opt-helpers.h, fix some comments

opt-helpers.h includes ccan/opt/opt.h anyway, and is a useful marker
for finding the GPL files.
xml-lang-classify: catch up with API change