Re-implementation of hotlist via general tree code. Animations can be stopped once more. Purged a few xcalloc() calls.
svn path=/import/netsurf/; revision=1394
Moved GIF file reading to image/, optimisation of plotting for GIFs, JNGs, PNGs and JPEGs, initial work for toolbar customisation. Possibly some other things too.
svn path=/import/netsurf/; revision=1301