ZMenus for title labels with cell line info.

(and minor regulation label tweak).
Remove horrible track_after, now we have sections.
Allow tracks to demure from having section label.
Fix cell line selector for labels with odd chars.
Fix: cell line is active even if only evidence on.
Fix cell type selection logic re track types.
Fix eveidence button bugs.
Only warn of no evidence if any ev. track is on.
Remove tracks from regulation summary page.
Segment off by default in featurecontext.
Cell line selector on sumamry page.
ZMenus change to point to regulation summary page.
Reg segs improvements.
Only one cell line by default in cell line view.
Remove harmless debugging code committed in error.