Estimate time to move to Qwt6

[martyngigg]

This is a requirement of the evaluation exercise

[martyngigg]

http://qwt.sourceforge.net/qwtchangelog.html

• our custom scale transforms will have to be ported to the new QwtTransform hierachy: 1w
• functionaility using qwt_picker needs to be examined and updated: 1w
• fixing issues with newer compilers and warnings about virtual method overrides: 3 days
• port all uses of QwtPlotCurve::setData to the newer setSamples API. Major decision is ensuring that unnecessary copies are not made: QwtPlotCurve::setSamples: 1m (including tests for performance/memory usage)
• see if the changes to legends have affected us (http://qwt.sourceforge.net/qwtchangelog.html#LEGEND): 1w ??

Rounding up to account for unexpected issues and more testing then this total 2 months.