Change the package to use "texi2any" instead of "texi2HTML"

[dasergatskov]

This is an initial attempt to use texi2any (and hence the modern texinfo processing) instead of texi2HTML.
Most of the changes in __texi2html__.m file:
Use html2any processor instead of texi2html (obviously).
@seealso handling is completely re-written.
<em> handling changed to keep <em class="math"> (I think this also fixed the bug in the old code.)

In function_texi2html.m and classdef_texi2html.m code to place "Source Code:" changed.
It is now relies on </dd><dl> marker.

I tested it on itself package_texi2html ("pkg-octave-doc") and on "statistics" and it seems to work.

There is still some debugging code left (temporary files are preserved with tmp1_ prefix rather than deleted,
errors/warnings from texi2any saved into *.log files).

Any comments are welcome.

Note, it still preserve the original handling of @@ in classnames. I think to change it to make it verbose (i.e. to render both of those symbolsane needs to have an additional diff totexi2html.m`:

         fname_file = strrep(fname, filesep, "_");
         my_see = strcat(new_see, "  <a href=\"", fname_file, ".html\">", fname, "</a>");
       else
-        my_see = strcat(my_see, fname);
+        ## Escape @ symbols to prevent HTML processing issues
+        escaped_fname = strrep(fname, "@", "&#64;");
+        my_see = strcat(my_see, escaped_fname);
       endif
       
       if (i < length(fnames))

(This is somewhat brute-force approach to avoid texi2any processing.)

das_texi2any.diff.gz

[S-Pithan]

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get_forge_pkg at line 72 column 7
get_forge_download at line 32 column 4
pkg at line 538 column 12