Tecplot Add-on: Plot3D <--> Tecplot converter

The two I/O packages employed by p3d2tec might benefit other applications reading or writing Tecplot and/or Plot3D data. Here are the utilities provided for applications:

   public :: Tecplot_read       ! Reads  an entire structured Tecplot file
   public :: Tecplot_write      ! Writes an entire structured Tecplot file
   public :: Tec_header_read    ! Reads  Tecplot file header records
   public :: Tec_header_write   ! Writes Tecplot file header records
   public :: Tec_block_allocate ! Allocates the array fields for one block or zone of a Tecplot file
   public :: Tec_block_read     ! Reads  one block of a structured Tecplot file
   public :: Tec_block_write    ! Writes one block of a structured Tecplot file
   public :: clone_header       ! Derives one dataset header from another
   public :: clone_zone         ! Derives one zone (block) from another and allocates array fields
   public :: deallocate_header  ! Deallocates any dataset auxiliaries in the given grid header
   public :: deallocate_blocks  ! Deallocates all array fields of the indicated blocks of a grid

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!  Module prompted by Tecplot 360 dataset auxiliaries.  Storing them with block 1 (only) was attempted !
!  but is not a good idea.  The dataset file name, title, and variable names, etc., belong here too.   !
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   module grid_header_structure
     type grid_header
        character          :: filename * 80           ! Name of file if the dataset is to be read or written
        logical            :: formatted               ! T | F for ASCII | binary
        integer            :: ndim                    ! 2 | 3 for 2D | 3D data (x and y only, or x, y, and z)
        integer            :: numq                    ! # additional variables beyond ndim; numq >= 0
        integer            :: nblocks                 ! # blocks in dataset (not always known?)
        integer            :: datapacking             ! Same for all zones;  0 => POINT; 1 => BLOCK (efficient)
        character          :: title * 80              ! Dataset title
        character, pointer :: varname (:) * 32        ! Variable names; embedded blanks are permitted; same length as in 
                                                      !    Tecplot_io
        integer            :: ndatasetaux             ! # auxiliary data strings associated with dataset; ndatasetaux >= 0
        character, pointer :: datasetauxname (:) * 32 ! Names of dataset auxiliary items, if any (no embedded blanks)
        character, pointer :: datasetauxvalue(:) * 32 ! Corresponding values (excluding leading and trailing double quotes)
     end type grid_header

   end module grid_header_structure

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!  Module for a structured grid block or zone with associated flow field variables and a zone name   !
!  (Tecplot_io_module version).  This version is a superset of that originally used with the xyzq_io !
!  package, and is intended to be compatible with that package.  If both packages are used by an     !
!  application, this version of the module is the one that should be compiled.                       !
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
   module grid_block_structure

     type grid_type
        integer            :: nzoneheaderlines        ! # lines in zone header, to facilitate reading zones after 
                                                      !    counting them
        character          :: zone_title * 32         ! Zone/block title; embedded blanks are permitted; same 
                                                      !    length as in Tecplot_io
        integer            :: nzoneaux                ! # auxiliary data strings associated with zone; nzoneaux >= 0
        character, pointer :: zoneauxname (:) * 32    ! Names of zone auxiliary items, if any (no embedded blanks)
        character, pointer :: zoneauxvalue(:) * 32    ! Corresponding values (excluding leading and trailing double quotes)
        real               :: solutiontime            ! Time (or some other useful real number) associated with zone
        integer            :: ni                      ! # points in i direction
        integer            :: nj                      ! # points in j direction
        integer            :: nk                      ! # points in k direction
        integer            :: mi                      ! # dependent variables in i direction
        integer            :: mj                      ! # dependent variables in j direction
        integer            :: mk                      ! # dependent variables in k direction
        real               :: xmin, xmax              ! Data range for the grid block in the x direction
        real               :: ymin, ymax              !     ... and the y direction ...
        real               :: zmin, zmax              !     ... and the z direction
        real, dimension(:,:,:),   pointer :: x,y,z    ! Grid coordinates
        real, dimension(:,:,:,:), pointer :: q        ! Dependent variables
     end type grid_type

   end module grid_block_structure