* Support PutDeferred() in ADIOS1 writer

* added PerformPuts() to ADIOS1Writer

* refactor toolkit/interop/adios1/ADIOS1Common in preparation for having separate Write and Read classes

* Working towards ADIOS1 Reader. Changes the Engine.BeginStep() signature for all engines.

* Updates to ADIOS1 reader, variables and scalar values are propagated now at Open

* fix ADIOS1 reader using the correct step selection values

* Support PutDeferred() in ADIOS1 writer

* added PerformPuts() to ADIOS1Writer

* refactor toolkit/interop/adios1/ADIOS1Common in preparation for having separate Write and Read classes

* Working towards ADIOS1 Reader. Changes the Engine.BeginStep() signature for all engines.

* Updates to ADIOS1 reader, variables and scalar values are propagated now at Open

* Support PutDeferred() in ADIOS1 writer

* added PerformPuts() to ADIOS1Writer

* refactor toolkit/interop/adios1/ADIOS1Common in preparation for having separate Write and Read classes

* Working towards ADIOS1 Reader. Changes the Engine.BeginStep() signature for all engines.

bug1: when writing value characteristic bpdump requires the length before the value
bug2: fixed merging serialized collective metadata index

examples/hello/bpTimeWriter/helloBPWriteStep.cpp

examples/hello/bpWriter/hellBPPutDeferred.cpp

BPWrite_c -> ctypes
XMLConfigTest.TwoIOs -> Test BP Writer 1

Callback Signature classes extend Operator
Operators can be used per Variable, IO or Engine

Continue refactoring IO, ADIOS classes

Changed m_Transports from vector to map, needed by subfile manager

BP3 Deserialization:
Getting subfile seeks and intersection info
Set host language in bindings for row-major and zero-index info

Passed ctest (MPI and nonMPI) excluding ADIOS1 engine, and Python bindings
HDF5, C bindings and C++ tests working
Introduced BeginStep EndStep functions
Renamed IO GetVariable/Attribute to InquireVariable/Attribute

Use a 2-pass approach to generate ADIOS2.config.  The first pass
generates the configurable options in the header and the second pass
configures them.  This allows for consistency in the options used and
thier ordering with respect to where they're used elsewhere.

Getting and defining available Variables at Open
Storing Variable position in Metadata, added to VariableBase
mpidummy: Added support for MPI_Reduce, MPI_Gatherv
Added utils and BPLS

Implemented basic buffer reading functionality
Added threading for bp serialization/deserialization
Refactored MPI functionality
Engine is now a reference
Initial Read API