[GRASS5] proj changes for releasebranch?

[Paul Kelly]

Hello
I feel the changes I made to the proj implementation in GRASS and the new
datum transformation support are now probably mature enough to go into the
release branch, so I have prepared this and will merge the changes in in a
day or two if nobody objects (positive encouragement would be good too).

Some other things that are intermingled with the proj stuff that will go
in as well:
Easy SG3d compilation by specifying --with-irisgl to configure (this can't
hurt anything)
r.sun improvements which were mixed up with the proj changes to r.sun and
seem to have got good feedback
geo.h and geo_init.c tidying by Eric Miller (seems to work fine in CVS
head)
d.where improvements to output lat/long or WGS84 lat/long for other
projections than UTM

Of course there are lots of other changes in the CVS head that should go
into the release branch; these are just a few that would have been a bit
of work to separate from the proj changes.

Paul