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

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

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

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

- Added examples/groupless/multistep writer example to the build
- Added ADIOS1 reader but it does not work yet
- Added heat transfer example reader

mpi and nompi:

helloBPWriter
timeBPWriter

Fix Variable.SetSelection(). heatTransfer adios2 writer is intentionally broken to keep to the intended API.