refs #7957. Add log scaling feature.
Revert "refs #7957. Add log scaling feature."

This reverts commit 0d49ebb5d33de98321b4e79bc53193a0b9d7bd17.
Revert "Revert "refs #7957. Add log scaling feature.""

This reverts commit a588b297a0d001ef12bcd74703003f7ec9c083ad.
refs #7957. Use older Qwt features for RHEL6.

Use range feature of Qwt to get the interval as the last implementation did not work cross-platform. Also fix the LineCurve type such that zeros can be ignored when in log scale.
refs #7957. Further fixes for old qwtplot versions.
refs #7957. Fix compiler warnings.
refs #7957. Fix works for Proper plot calc from slice.

The fix does not cover the preview plot. For some reason the Preview plot ends up with a 0,1,0,1 bounding box.. This will require some further investigation.
refs #7957. Remove custom CurveData

QwtPlotCurve can be used and does the right thing. Fix AutoScaleAxis usage.
Merge remote-tracking branch 'origin/feature/7957_log_scale'