Modifications are mainly described in doc/changelog.md.

In short:
- QUERY_REQUEST is now named QUERY
- QUERY_REPLY is now named ANSWER
the two messages are now bidirectional.

This feature was not working nor following the protocol.
This is now tested thanks to batsched new version.

Version is no longer hardcoded in the source code.
The source code simply reads its BATSIM_VERSION macro.

BATSIM_VERSION is set by CMake.
(if Batsim is compiled without it, it sets version as vUNKNOWN_PLEASE_COMPILE_VIA_CMAKE)

Version is retrieved from git-describe.
If git is not available or if Batsim is built from a tarball, a default version is used.
This default version is hardcoded in CMake.

Also add more test on sequential jobs

This reverts commit fe162ee2.

All options no longer require a short name.
-> rare options are only long now.

Some options have been renamed to sound clearer.
--mmax, --mmax-workload, --enable-sg-process-tracing,
--allow-time-sharing, --workflow-jobs-limit, ...

Some default values have been changed for consistency.
--mmax and --workflow-jobs-limit both have 0 as
default unlimited value.

Running batsim --help should now be more readable, and
display what can be done via the CLI.

In order to have deterministic workload names, I chose to use a hash function
rather than an uuid. The workload names are now the first 6 characters of the
hexadecimal representation of the SHA-1 of the absolute file name of the
workload file.

The regex part of the C++11 standard was not implemented before june 2015.
To avoid forcing users to have a very recent compiler, switching to boost instead.