[Gitstat-devel] Updating the db via admin.php is now possible

Hi

I've added the 'infrastructure' to update the schema of the db. This makes it 
possible to create the initial database (not used yet) and also to update to the 
latest schema. The updatedb() function takes care of all intermediate steps.

This means that all additions to the schema should go via the newly created 
libdb.php and not via single sql-scripts. For now we should add the complete 
schema also to install/sql/gitstat.sql but this file will be removed in the 
(nearby) future to be replaced by a installation 'infrastructure'.

(reminder to self to add gitstat_settings to gitstat.sql)

Next thing I will do is add a field to the v_tag table to indicate whether a tag 
should be visible or not in the graph creation. This will be a major step away 
from the current kernel-centric gitstat.

Once the installation infrastructure is there I think we should launch a new 
version, 0.4.

As always, comments/remarks/suggestions are welcome.

Cheers,

PAul.