Export line values (from line plot board) does not match units used in plot

[Angus Yeh]

The original behaviour was exporting the "raw" values extracted from model.

The disadvantages: - misleading, user think they are exporting the values seen on the plot. - JPO observed that it's annoying as once load back in, it won't be the same unit.

Hence this is considered a bug, and the behaviour should be changed.

--> will now convert to displayed units before save to text file.

[Angus Yeh]

Fix issue #67, apply displayed unit to value exporting from line plots.

→ <<cset 9ae34acceeae>>