Fix LogScale mode of vtkAxis.

This change is to address ParaView bugs 13876, 13877, and 13899.
It removes LogScaleReasonable and the associated logic which was
contributing to nonsensical ranges for logarithmic axes.

This patch also adds methods {Get,Set}Unscaled{Minimum,Maximum,Range}()
so that fixed ranges may be specified in the same coordinate
system as the source data. The versions of these methods without
"Unscaled" in their names expect log-values to be passed or
returned when LogScale is true, which is difficult for user-interface
code to track.

Additional changes are required to address the test case of
ParaView bug 13899. With these changes, the minimum and maximum
limit values are properly transformed when switching to and from
log-scaled axes.

Plots that rely on axes to determine scaling are fixed
to refer to the active scaling (GetLogScaleActive) instead of
the desired scaling (GetLogScale)..

Change-Id: I1a4a3882bbeab2484145f4a75a6430cf6a0cea42
Merge topic 'fix-vtkaxis-log-scaling' into master

1412cda2 Fix LogScale mode of vtkAxis.