-move palette interpolation setting away from main toolbar

-about dialog

-history

 -GUI for showing/manipulating it

 -saving/loading of single positions and complete history lists

-online help

-coloring algorithms

 -saving/loading

 -accepting them in infix notation

  -http://www.maths.abdn.ac.uk/~igc/tch/mx4002/notes/node72.html has an
  algorithm for converting infix to postfix.

-use long double when double's precision runs out (~30% slower)

 -probably by templatizing all the calculation functions

-optionally store iter/re/im for each calculated pixel, so you can tweak
 coloring without recalculating image (needs 12 bytes per pixel -> lots
 of memory needed for large AA values)
