
The PLOT3D reader is not fully fleshed out.
It was recently enhanced greatly by Abel Gezahegne to support all files
described in the PLOT3D documentation described at:
http://www.nas.nasa.gov/FAST/RND-93-010.walatka-clucas/htmldocs/chp_21.formats.html
I also tarred up the contents of that page and added it to this directory
(located in plot3d_html.tar).

We should support structured, unstructured, multi-grid, single-grid,
iblanked, non-iblanked, ascii, binary, compressed ascii (ex: 200x1.63), and
all combinations.  That said, test data was sparse, so the reader may not work
for some of these variants.

Other test datasets, claiming to be PLOT3D variants, were discovered that
were not compliant with the "Chapter 21" documentation.  These datasets
all appeared to be tied to EnSight.  Also, they all appeared to have extra
integers at the beginning of their grid files (beyond what could be explained
by having a multigrid file).

In addition, PLOT3D is not a self-describing format.  The way to get around
this is to have the user tell us what variant it is.  This can be done
through a database window.  Since that is not currently available, it can
also be done through a text file.  The text file specifies which variants
the current PLOT3D file is.

The text file must have the extension ".vp3d".

Below is an example of the text file:
% cat NHLP_2D.v3pd
# Files:
#
# Note: the Grid file and Solution file fields do not have to be specified.
# If they do not appear, VisIt will assume that the .vp3d should be replaced
# with ".x" for the grid file and ".q" for the solution file.
#
GRID NHLP_2D.g
# SOLUTION NHLP_2D.q

# Single/Multi Grid.  Single grid will be assumed if no value is specified.
#
# Options:
MULTI_GRID
# SINGLE_GRID

# Data encoding, ASCII or Binary  Binary will be assumed if no value is
# specified.
#
# Options:
#BINARY
ASCII

# Endianness.  This only applies to BINARY files.  Native endian will
# be assumed if no value is specified.
#
# Options:
#LITTLE_ENDIAN
#BIG_ENDIAN
#NATIVE_ENDIAN


# Structured grid vs unstructured grids.  Structured grids will be assumed
# unless stated otherwise.
#
# Options:
STRUCTURED
#UNSTRUCTURED


# Iblanking.  No iblanking is assumed unless stated otherwise
#
# Options:
# NO_IBLANKING
# IBLANKING


# 2D vs 3D.  3D will be assumed unless stated otherwise.
#
# Options:
2D
# 3D

# Precision.  Single precision is assumed unless stated otherwise
#
# Options:
SINGLE_PRECISION
# DOUBLE_PRECISION


# Compression.  This only applies to ASCII files.  Some codes compress
# repeated values as 4*1.5 as opposed to 1.5 1.5 1.5 1.5.  It is assumed
# the data is not compressed unless stated otherwise.
#
# Options:
# COMPRESSED_ASCII
# UNCOMPRESSED_ASCII

# C vs Fortran Binary.  Fortran Binary is not supported.  This option is for
# future support.  C-Binary is assumed.
#
# Options:
# C_BINARY
# FORTRAN_BINARY
