dists: remove all dists specific stuff

Since the move to git, it's much more practical to have an official repository
as "clean" as possible.

Therefore, I'm putting all packaging specifics outside the repo, explaining
where to find it. This only makes official what happened since a while, as the
dists/ dir is no accurate anymore.

Note that we work even more closely with packagers than before. This enables a
much faster integration and factoring of patches, as it factors out much of the
noise.
README: add some light on what happens to contributions
plugins/Pgsql.pm: add multigraph support

A new 'multigraph' parameter makes it possible to use the module to create
multigraph plugin.

The existing 'extraconfig' parameter was not suitable for this purpose because :
- general query output modification is required
- it outputs in the middle of the config output
plugins/Pgsql.pm: allow multiple graph types

This feature extends module flexibility by allowing user to specify certain
graph type in 'graphdraw' parameter for each counter. If you specify an array of
graph types in the form below (assuming you have three counters):

    graphdraw => [ AREA, LINE1, LINE1 ]

Then graph type for each of the counters will be set according to the elements
of the array.  Graph types elements need to be specified in the order or being returned
by 'configquery'.
Merge branch 'pg-enh' into devel