Adapt heat transfer example to support MemorySelection

     * contiguous memory pointer passed at Put from which data starts. e.g. if

     * variable.Start() = {rank*Ny,0} and there is 1 ghost cell per dimension,

     * then memoryStart = {1,1}

     *

     * 		memoryCount: local dimensions for the contiguous memory pointer

     * passed at Put, e.g. if there is 1 ghost cell per dimension and

     * variable.Count() = {Ny,Nx}, then memoryCount = {Ny+2,Nx+2}

     *

     * </pre>

     */

    void SetMemorySelection(const adios2::Box<adios2::Dims> &memorySelection);

+-------------------------+---------+---------------------------------------------+

| Application             | Engine  | Description                                 |

+-------------------------+---------+---------------------------------------------+

| File                    | BPFile  | DEFAULT write/read ADIOS2 native bp files   |

| File                    | BP3     | DEFAULT write/read ADIOS2 native bp files   |

|                         |         |                                             |

|                         | HDF5    | write/read interoperability with HDF5 files |

+-------------------------+---------+---------------------------------------------+

    'utilities/bpls.rst',

    'engines/dataman.rst',

    'engines/hdf5.rst',

    'engines/bpfile.rst',

    'engines/bp3.rst',

    'engines/sst.rst',

    # 'engines/engines.rst',

    # 'faq/faq.rst',

******

BPFile

******

*************

BP3 (Default)

*************

The BPFile Engine writes and reads files in ADIOS2 native binary-pack (bp) format. BP files are backwards compatible with ADIOS1.x and have the following structure given a "name" string passed as the first argument of ``IO::Open``:

The BP3 Engine writes and reads files in ADIOS2 native binary-pack (bp) format. BP files are backwards compatible with ADIOS1.x and have the following structure given a "name" string passed as the first argument of ``IO::Open``:

.. code-block:: c++

.. note::

   BPFile names are compatible with the Unix (/) and Windows (\\) file system naming convention for directories and files.

   BP3 file names are compatible with the Unix (/) and Windows (\\) file system naming convention for directories and files.

.. caution::

   The default BP3 engine will check if the ".bp" is the extension of the first argument of IO::Open and will add ".bp" and ".bp.dir" if not in the name

This engine allows the user to fine tune the buffering operations through the following optional parameters: 

7. **MaxBufferSize**: maximum allowable buffer size (must be larger than 16Kb). If to large adios2 will throw an exception.

8. **FlushStepsCount**: user can select how often to produce the more expensive collective metadata file in terms of steps: default is 1. Increase to reduce adios2 collective operations footprint, with the trade-off of reducing checkpoint frequency. Buffer size will increase until first steps count if MaxBufferSize is not set.

8. **FlushStepsCount**: users can select how often to produce the more expensive collective metadata file in terms of steps: default is 1. Increase to reduce adios2 collective operations footprint, with the trade-off of reducing checkpoint frequency. Buffer size will increase until first steps count if MaxBufferSize is not set.

9. **SubStreams**: (MPI-only) user can select how many sub-streams ("M" sub-files) are produced during a run, ranges between 1 and the number of mpi processes (N), adios2 will internally aggregate data buffers (N-to-M) to output the required number of files. Use for performance tuning.   

9. **SubStreams**: (MPI-only) users can select how many sub-streams ("M" sub-files) are produced during a run, ranges between 1 and the number of mpi processes from MPI_Size (N), adios2 will internally aggregate data buffers (N-to-M) to output the required number of sub-files. If Substream is out of bounds it will pick either 1 (SubStreams < 1 -> N-to-1) or N ((SubStreams > N -> N-to-N) and ADIOS2 will issue a WARNING message. Use for performance tuning.   

==================== ===================== =========================================================

 **Key**              **Value Format**      **Default** and Examples 

 MaxBufferSize        float+units >= 16Kb   **at EndStep**, 10Mb, 0.5Gb   

 BufferGrowthFactor   float > 1             **1.05**, 1.01, 1.5, 2 

 FlushStepsCount      integer > 1           **1**, 5, 1000, 50000

 SubStreams           integer >= 1          **MPI_Size**, ... MPI_Size/2, ... , 2, 1  

 SubStreams           integer >= 1          **MPI_Size (N-to-N)**, MPI_Size/2, ... , 2, (N-to-1) 1  

==================== ===================== =========================================================

3. :ref:`Runtime Configuration Files` in the :ref:`ADIOS` component.  

.. include:: bpfile.rst

.. include:: bp3.rst

.. include:: hdf5.rst

.. include:: dataman.rst

.. include:: sst.rst