Added GetVariableBase* in IO needed by C bindings and real-time
applications, nullptr is a valid state in return.

Added c bindings test under testing/adios2/bindings/c
Updating ReadMe.md to include ADIOS2_USE_C for C bindings

Builds libadios2_c.a and libadios2_c.so 
Verified with and without MPI
Added nonMPI hello bp write example
Added new ADIOS2_USE_C ON/OFF cmake argument

To do:
Add C tests and cmake support for the latter

signed char needed by int8_t in C bindings
Added tests

Added portable PathSeparator
Fixed format for bp file name

Fixed conflicts for clean compilation
Fixed clang-format
Adding free in C example

Added working example examples/hello/bpWriter/helloBPWriter.c
Changed Engine signature to resolve Write void* at runtime (required by
C bindings).

To do:
CMake infrastructure
Testing

Makefile compiles

To do:
CMake infrastructure
Verify struct adios2_Engine  forward declaration
Add tests

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

Restoring std:: for cstdio functions
Removing warnings explicitly with pragmas

Removed ADIOS copy constructor explicitly, as it wasn't allowed by clang
compiler in testing/xml/TestXMLConfig.cpp

Using more portable preprocessor definitions to avoid warning on Windows
for ctime and fopen

Introduced std::throw_with_nested for bad_alloc in STLVector Capsule

Removed std:: in C function calls to avoid confusion with actual C++
only calls

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

Using language primitives in test data instead of fixed width integers.
casting size_t to unsigned long in mpidummy to remove warning on Mac

Added test for generating profiling.json
Fixed inclusion for NLohmannJson json.hpp in Test
Tested resulting profiling.json on R (jsonlite), Python (json)
and C++ (json for modern C++)

Missing file_index characteristic in BP1Writer metadata

Fixes #153

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

Checking std::ios_base::failure exceptions
IOChrono is off by default, each owner turns it on explicitly
Modified FileDescriptor and FilePointer destructors
Added Tests BPWriteRead for stdio and fstream
Removed IO AddTransport with vector (shoud have been there?) to enable
AddTransport in Tests

Fixes #152

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

Replace std::copy with std::memcpy in std::thread
Added threads to profiling.log
Limiting the use of threads

TO DO: large scale runs to enforce threads policy

If file doesn't exist, continue with run
Fixed bug if space before and after "=" in: <tag attribute1= "value1">

To do: need to discuss policy for config files, still experimental