Handle RA that spans 0°

[rknop]

Make sure code handles RA spanning 0° properly.

q3c should do this properly (I hope!)

Build in an assumption that no FourCorners object will span more than 90° in RA (which is already absurdly large).

Things to do:

• FourCorners : if maxra-minra > 90, swap them (so minra will be between 180 and 360, maxra will be betwen 0 and 80).
• Make sure the custom gaia rect server does this right
• Make all insertions into a FourCorners object sets maxra minra right
• Add minra, maxra columns to speed up searching (so we don't have to look at all four corners to figure out if it spans 0)
• other things...

[rknop]

Turns out that the custom gaia rect server already does this right (whew).