
- add indication when labels are not drawn due to lack of space within label track
  - small +n text at r1?

- improve SVG output
  - groups via <g>
  - style sheet
  - add transparency and dashed line support

- fix relative radius interpretation (inner/outer) based on r0,r1 values

- filter ideogram display based on presence/frequency of links to other ideograms

- zoom regions based on data density

- filter ideograms based on number of data points

