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

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

Picking up config.xml from examples/heatTransfer/write/config.xml from
./build/bin/heatTransfer_write_adios2

Increased Default Maximum Memory to 200Mb
Added config.xml for the heat transfer example for memory management
(among other parameters) at runtime 

To do:
Copy config.xml to /build/bin, right now the heat transfer example won't
run in config.xml is not found

Keep only std::map<std::string, std::string> initializer list.
Corrected examples. 

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

bool flag checks are implicit
Removed single letter enums in ADIOSTypes.h
All enums are enum class in ADIOSTypes.h using CamelCase
ADIOS uses delegating constructor
Using return type of emplace for IO (in ADIOS) and Variable (in IO)
Removed all base class include from inl template file