[Gpe-list] Changes to libgpepimc API

[Graham Cobb]

I needed to add a capability to libgpepimc to reload the categories from the 
database and while I was in there I decided to make some changes to the API 
to hide the internal data structures.  Note that these changes are not 
backwards compatible, but I am making all necessary changes to the GPE 
components which use the API.

The changes visible to the API consumers are:

1) The struct gpe_pim_category becomes opaque -- it is no longer declared in 
the public API header file and no consumers should need it.

2) gpe_pim_category_rename and gpe_pim_category_set_colour update the 
in-memory data as well as the database.

3) gpe_pim_categories_list returns a list of category ids, instead of category 
addresses.

4) The libtool version-info has been increased to 1:0:0 because the API is 
incompatible.  This means that the SONAME will change and the debian package 
will want to become libgpepimc1 (instead of libgpepimc0).

I plan to check in these changes, and the corresponding changes to API 
consumers, tomorrow (Saturday), unless anyone objects (or I find problems).

Graham