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

Continue refactoring IO, ADIOS classes

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

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

Refactored IO, Variable class due to common functionality

Wrapper classes CompressBZip2 and CompressZfp implemented
Under transform/compress and adding examples and tests
Added/Modified cmake files
Makign changes to cmake from PR review

To do:
Add more tests

Bugs: 1) Missing binary mode in FilePointer fopen and FStream ofstream
transports
      2) Replacing reinterpret_cast of size_t to uint_64, not the same
on Windows 64-bit

Removed some warnings generated by Visual Studio

Added static_cast for type conversions

Refactor XML reader to restore original check on single engine
conditions and eliminate warnings. Test added.

Allow ctime and fopen "not secure" warnings: now using binary fstream as
default file IO library on Windows

Fixes #153

Fixes #152

Added example bpFlushWriter (incomplete).

Python bindings running but not printing values with bpls. Min and Max
captured correctly.

IO SetParameters and AddTransport will accept vector and map

Variable.cpp and Variable.tcc for complete separation of core components
in the public include

1 Now IO (replaced Method) and is the factory for Variables and Engines
2 Reduced core components to user-public objects only
3 Moved and reorganized all helper functions to helper directory
4 Engines are now lightweight (except for ADIOS1Reader WIP) using MACRO
5 HF5Common and ADIOS1Common (except for Readers WIP) are now part of the toolkit so they can be reused by Engines
6 TransportMan is a new layer for transport management (file is default)
7 DataMan will be implemented under toolkit/transportman/dataman
8 Template separation (tcc and inl) applied all over the code
9 Improved Doxygen documentation

Runtime Issues:
DataMan library compilation (cacheman)
ADIOS1 Warning
TestADIOSInterfaceWrite catches exceptions