log functions

[Rodrigo Moya <rodrigo linuxave net>]

Hi all!

I've finished the first version of the log viewer, which reads the files
generated with the gda_log_* functions (in libgda-common). Right now,
only the gda-interbase and gda-ldap use these functions. So please,
change, in the providers, whenever you can all the g_warning, g_error,
g_print, g_log, etc with the corresponding gda_log_* calls.

The gda_log functions use the gnome_config file format, using dates as
section names, and clock time as key names. Thus, the log viewer can
show the logs by dates, times, etc, which is much better than looking at
a plain text file.

Cheers