- Add header to all BP4 data files, metadata files and index table

Report the availability of RDMA for Staging in CMake summary

- Modify header content:
  - 32 bytes Tag string e.g. "ADIOS-BP v2.3.1 Index Table     "
  - byte 36 endianness
  - byte 37 BP version
  - byte 38 Active flag (in Index table it indicates active writer)
- bp4dbg print header for all files
- bp4dbg just seeks over real data instead of reading it

  fix a potential problem in WriteCollectiveMetadataFile() function
  clang format
  fix the bug in doclose function for BP4 engine

Test HDF5 with simple tests

Additional documentation improvements.

* release:

  Use CTest fixtures in Install tests
  Use MPI in C install test
  Re-enable Install tests

* release:

  fix travis errors
  Print content of array attributes, in metadata as well as in data file. Format idx table better.

* release:

  Fix Sst Docs WRT behaviour in no reader case

* release:

  Backing off to avoid SSC failures
  Problems in MPMD mode unless running serial
  Add SSC tests
  Try for MSVC
  Try for MSVC
  More common tests
  More common tests

* release:

  Default engine is BPFile, i.e. as of today, for writing it is always a BP3 engine, for reading it is BP3 or BP4 depending on the file it is opening.

Print content of array attributes, in metadata as well as in data fil…

Fix Sst Docs WRT behaviour in no reader case

More common tests

Default engine is BPFile, i.e. as of today, for writing it is always …

Fix broken Install tests

Default engine is BPFile, i.e. as of today, for writing it is always a BP3 engine, for reading it is BP3 or BP4 depending on the file it is opening.

Fixtures were initially not used because Adios supports CMake 3.6,
which did not yet have fixtures (they were introduced in 3.7.)
However, adding the fixtures can be done in a backwards compatible
manner without affecting pre-3.7 builds. Add test fixtures to ensure
that Install.Setup always gets run before the other Install tests, even
if it's not specified in the CTest -R regex. (Note that we are still
using the DEPENDS property in addition to FIXTURES_REQUIRED in order
to support 3.6.)

* release:

* commit 'd93747d5':
  remove debug prints in BP4 serializer
  Fix flake8 errors
  Install all .py files for bp4dbg
  bp4dbg: dump metadata too. Print values for characteristics and attributes. Fix: BP4 and BP3 attribute length in data was written as 8 bytes and the wrong value; now writing the correct length and on 4 bytes only.