* Added mouse-over 'tooltips' to CanvasFeatures tracks that show
a feature's label and description when the mouse hovers over
it. Thanks to Daniel Kasenberg for implementing this.
* Strand arrowheads in CanvasFeatures tracks now attempt to stay
visible on the screen, like they do in HTMLFeatures tracks. Thanks
to Daniel Kasenberg for implementing this.
* Fixed bugs and inefficiencies preventing JBrowse from handling very
dense BigWig files. Thanks to Michael Axtell for pointing this out
* Fixed a bug in which features were not always laid out correctly in
CanvasFeature tracks when the display mode is set to "compact".
* Fixed a bug causing the text labels of mismatching bases in
Alignments2 tracks (i.e. `Alignments` canvas glyphs) to be slightly
misaligned vertically when feature labels are turned on (they are
off by default for Alignments glyphs).
* Fixed a bug preventing the `defaultTracks` configuration variable
from operating correctly.