help as m-files

[Søren Hauberg]

Hi All,
  Attached is a fairly large changeset (hence the need for compressing
it) that re-implements the help system as m-files. This is pretty much a
fresh implementation, so there will be bugs (although I've removed those
I've been able to find). So, why would we want to re-implement this as
m-files, when we have something that's already functional?

  * It simplifies the code quite a bit, which should make it easier for
    new people to hack on. Especially, the 'lookfor' implementation is
    a lot more simple.

  * It provides some new functionality to Octave. Specifically, it is
    now quite easy to get the help text of a function, and run it
    through 'makeinfo'. This makes it fairly simple to generate html
    versions of the help texts.

  * 'lookfor' is now very fast. The new implementation of 'lookfor' can
    use cached help texts, which makes it very fast. For me, a call to
    'lookfor' usually takes less than a second (compared ~1 minute
    before).

The patch is, however, not entirely complete. To generate caches for
'lookfor', you need to run the 'gen_doc_cache' function. Basically,
'gen_doc_cache' traverses the current path, and creates a cache file in
each directory. This should either happen during 'make' or 'make
install'. I'm not sure which is better, so I'd appreciate some help
here. Also, this should happen during 'pkg install' such that the user
can search package help texts fast.

I also have the following on my outstanding-issues-list:

  * Perhaps move internal variables (eg 'makeinfo_program') to m-files?
  
  * how should 'private' directories be treated in Makefiles ?
  
  * Fix XXX's in code (nothing major).

Søren

mfile_help.patch.bz2
Description: application/bzip