[Kst] HPIC update

[Theodore Kisner]

I've had some conversations off-list with Andrew and Rick about the display of 
healpix maps.  I think we can whip something together fairly easily.

As for possible refactoring before adding more types of plots- I know George 
is busy right now, and it seems like this may not be the best time to start 
talking about reorganizing the KstDataObject / Kst2DPlot interaction.  Such a 
change would require touching huge amounts of code.  It might be better to 
put things like that off until 1.3 or even 2.0.

Given that, the "quick" way of implementing healpix maps is the following.  If 
this sounds ok, I'll start working on this (with input/help from Rick):

0.  The HPIC datasource provides us with a full-sphere map stored in a 
KstVector.  The nside, ordering, etc can be accessed (approximately) from 
KstRVector->_file->_metadata.  If the HPIC datasource is not accepted into 
SVN for political reasons, then hopefully any "replacement" healpix 
datasource would provide similar information in the form of KstVector + 
metadata.  I would think that the plan below is independent of the choice of 
healpix datasource... 

1.  Create a new class that is analogous to the KstMatrix/KstImage combination 
(class KstHpic : public KstDataObject).  This will store information about 
how the map is to be displayed.

2.  Add a list of these objects to Kst2DPlot.  Add a draw function.

3.  Add more dialogs to let users configure the display properties.

4.  command line bindings (e.g. kst -z 2 map.fits) and anything else.

If there are no complaints, I'll start working on a finely-grained patchset to 
do this.

cheers,

-Ted