Features wishlist

• display an Aladin Lite window, centered on a given position, with a given field of view
• switch to another HiPS
• zoom
• change color map
• pass an astropy Table object and display it
• add markers at given positions
• load VizieR, NED, SIMBAD data
• Retrieve data in IPython from Aladin Lite:
  • position of view center
  • loaded catalogues as astropy Tables
  • request a FITS cutout of the current view, for the current displayed HiPS
  • request a JPEG thumbnail of the current view
• list available HiPS at a position, with some additional filters
• Add callbacks:
  • on pan
  • on zoom