gitignore: add files from the js branch
treedrawing.contextMenu.js: don’t project indices of traces into context menu

fixes #42
treedrawing.utils.js: fix corner case in shouldIndexLeaf

it would not return true for leaves of the form (X *-1)
util.py: add debugging code for issue #45
add urtext

fixes #38
add token id to urtext display

fixes #43
news for 1.2.1
version 1.2.1