[libvoikko] Preparing for libreoffice-voikko 4.0

[Harri Pitkänen]

In order to simplify maintenance and to smooth the upgrade path for future 
releases I have decided to drop all compatibility for LibreOffice <= 4.0 on 
the master branch of libreoffice-voikko. The next release will be called 4.0 
and requires LibreOffice 4.1 or later.

Reasons for this are:

 * The -BUCR issue described in the previous mails.
 * Some APIs have been deprecated. They are still available in LibreOffice 4.1
   but may go away in future releases. We can now stop using these APIs and
   hopefully make the extension slightly more forward-compatible. This is
   important especially on Windows where users may not upgrade all extensions
   when they upgrade LibreOffice.
 * We can hopefully fix the OS X build issues. Now we can assume that OS X is
   Intel-only and at least version 10.6 of OS X SDK is available for building.
   I already cleaned the Makefile a bit but there are some other changes that
   need to be made by someone who can actually test the build.
 * We could change the extension license to MPLv2/LGPLv3+ dual license which
   would allow including the code directly in LibreOffice.
   - Note 1: I still need to check whether I really am able to relicense the
     whole code but this looks quite likely.
   - Note 2: It is still too early to actually submit this for inclusion into
     LibreOffice as libvoikko is still GPL-only in production configuration.


It is possible to make releases of libreoffice-voikko 3.4.X if there is still 
any need, but I doubt it. In short,

  - If you need to be compatible with older LibreOffice releases, use 3.4.1
    and build against the oldest release you want to support. The binary
    builds will still work with LibreOffice 4.1 and maybe even later.
  - If you need to build with LibreOffice 4.1 or later, use the upcoming 4.0.
    You won't be able to use the extension with LibreOffice 4.0 or earlier,
    but compatibility with future releases might be preserved longer.

Harri