TODO

FEATURES

++ add groups in SVG output
+ add dashed line support in SVG output
+ add ability to place a label anywhere on the image based on pixel value (and maybe gravity) (e.g. create label in center of image)
+ add phylogenetic tree track
+ fix/improve/rewrite how text labels are put down in text track (currently this feature is nastily implemented)

IMPROVEMENTS

+++ add drop_line=yes drop_edge=yes to histogram bins
++ background (axes, outline, panel) for tracks is shown even for ideograms for which there is no data - fix this
+ when r0 or r1 is set to 1r, this is currently taken as the outer ideogram radius. Change this so that either inner_ or outer_radius are used, depending on the other r value in the pair (e.g. r0=0.5 r1=1r should use inner_radius for 1r, but r0=1r r1=1.2r should use outer_radius).
+ add the ability to define ideogram size in the image based on total fraction of the circle 

BUGS

++ verify that pairwise tag in the ideogram spacing blocks works - I've been having problems