[libvoikko] HFST backend is no longer experimental

[Harri Pitkänen]

HFST backend of libvoikko is no longer experimental. It should be nearly ready 
for release and I would like to ask you to test it as much as possible so that 
we know if it works on all relevant platforms.

If you use LibreOffice 4 and latest versions of libvoikko and libreoffice-
voikko from

 https://github.com/voikko/corevoikko
 https://github.com/voikko/libreoffice-voikko

and a Meadow Mari speller you should be able to see something like this:

  http://www.puimula.org/htp/tmp/mhr-speller-in-libreoffice-4.png

To install a HFST speller simply drop the ZHFST archive under ~/.voikko/3/
The name of the file does not matter as long as it ends with .zhfst
Restarting LibreOffice should be enough to have it notice the new speller.

Some things to keep in mind:

- Although the HFST backend is now stable it will not be enabled by default. 
You still have to configure libvoikko with --enable-hfst. This is to make the 
life easier for Linux distribution packagers who may need some time to get the 
required dependencies packaged. If they are even going to do that in the near 
future. A library configured without HFST support is still valid but it will 
of course ignore version 3 spellers.

- Hfst-ospell is required for this thing to work. It must be configured with 
all optional features (support for ZIP decompression and XML parsing) or 
things will break badly.

- I have used Hfst-ospell from SVN trunk and found some small bugs. Patch is 
attached to this bug report: http://sourceforge.net/p/hfst/bugs/165/
Later I noticed some more memory leaks coming from "voikkospell -s", those 
still need to be investigated and fixed.

- Previous support for installing HFST spellers under ~/.voikko/2 and using 
voikko-fi_FI.pro for metadata is now gone. Legacy HFST spellers (without zip 
container) are no longer usable with libvoikko. Other experimental backends 
continue to use the old voikko-fi_FI.pro hacks as before.

Harri