Linker error using different TimeScaleDraw::label but
also a memory leak with unneccesary calls to create a
new ScaleDraw object.
Also applied recent fixes from qwt6 for scale draws. We
should look to pick up some of the other recent fixes
-- especially QT5 support.
Fixes#363.
Upgrade to QWT 6.0.1, but still uses a locally patched copy
since support for 8 axes has not been included, despite it
being a relatively simple patch.
Fixes#634.
Fixes#567.
The patch that was applied was missing a number of critical changes
and needs to be recreated and retested. The majority of qwt was not
uplifted and remained at Qwt 5.
This reverts commit e97aac7919.
