- Can occur if the selected geometry does not actually exist.
  A non-critical bug since paraview catches this anyhow and
  just emits a warning message.

- The reader module allows two levels of caching.
  The OpenFOAM fvMesh can be cached in memory, for faster loading of
  fields. Additionally, the translated VTK geometries are held in a
  local cache. The cached VTK geometries should incur no additional
  overhead since they use the VTK reference counting for their storage
  management.

- this greatly simplifies data management and opens the possibility of
  reusing converted vtk meshes instead of converting each time.

- has the selected values directly and use these lookup names to store
  directly into a hash. This replaces several parallel lists of
  decomp information etc and makes it easier.

- improves the overview of the code

- avoids potentially issues if we reusing a vtkPoints array,
  and should be marginally faster without the additional
  range checking.

- adds flexiblity and reduces risk of memory leaks as we add/change
  features

STYLE: adjust naming for paraview internal polyDecomp

- also use updated forAll* macros

- add support for patch names in block mesh reader.

- as originally intended years ago, but never actually done.

- use 'foamPvCore' instead of 'vtkPVReaders' to avoid potential name
  collisions with any 'vtk*' files and since we may reuse these
  functions in other foam-paraview modules (not just readers).

STYLE: use same font size/colour for patch-names as for point-numbers

BUG: repair issue with single time-step

- paraview time-selector returns '0' as the requested time if there is
  only one time step. However, if we have skipped the 0/ directory,
  this single time step is likely a non-zero value.

- remove old (ParaView-3) files

- Works in 4.4.0, 5.0.1, 5.2.0 etc

STYLE:
- slots now use SM properties directly without a second lookup.
  This reduces exposure of the QT elements and simplifies the coding.

- avoid focus borders on the Qt elements

- place the "use Polyhedron" checkbox into a column

- move "Cache Mesh" down in the GUI (an advanced feature and thus
  should be less prominent)

- obtain button labels/tooltip directly from the XML content

This reverts commit c5bea524.

This reverts commit b18f6cc1.

- avoids things like "volPointInterpolate(U)", but will likely cause
  issues when used together with identically named Lagrangian fields!

- Include Sets/Zones now scans immediately to refresh the list of available
  mesh parts. Unfortunately, this also causes the object panel to be
  modified, even although the selection doesn't acutally need to change.
  This seems to be due to how the pqNamedWidgets are getting the information
  from the proxy properties. I can't figure if it's possible to acheive what
  I want, but we can probably live with the current implementation.

  After IncludeZones, simply us 'Reset' to undo the spurious GUI changes.
  Works fine - just looks a bit silly.

- Added 'Refresh' button to rescan for new times/fields.  Good for
  post-processing ongoing calculations without exiting the reader.

- Added 'Skip Zero Time' checkbox: many (some) calculations have
  data missing at time=0 (eg, rho, lagrangian, etc). This provides
  a convenient way to skip over this time.

- Future?:
  We could probably pick up favourite default values for these switches from
  ~OpenFOAM/controlDict, from a case system/paraview, or simply by making
  the casename.OpenFOAM also be an OpenFOAM dictionary with the settings.

- remove patch/point text labels upon deletion

- combined client/server plugin instead of separate .so files
  first experiment with adding panel decorations

- directory reorganization