Include ld-decode build number in debug

[Gamnn]

It would be useful to keep track of which specific ld-decode commit was used to decode a .tbc, perhaps in a comment at the top of a .json?

[simoninns]

In the videoParameters would be the best place, as that is only included once per JSON file. Then the info would be available to the tool chain too.

[simoninns]

Related to #290 - the build number should be included in the ld-decode debug log file (changed issue title)

[simoninns]

I've added the following to the top-level makefile:

BRANCH = $(shell git rev-parse --abbrev-ref HEAD)
COMMIT = $(shell git rev-parse --short HEAD)

These variables should be fine for importing into the Python stuff too @happycube and then added them to the JSON if desired.

The ld-decode-tools qmake .pro files have been altered to pull these in as defines (there is also a default in case compilation is local in Qt Creator (sets both to "unknown").

All tools will now report commit and branch using the --version switch. The TBC library has also been altered so the commit and branch is included with the first debug message to pass through the library.

[simoninns]

This is what it looks like from the tools:

[Gamnn]

Just a thought, but a compatibility version would be useful too, for the .TBC json. This could help with any changes to the format (e.g. for #242) that would break tool compatibility with old decodes.

[happycube]

Trying to figure out how to copy this into a 'make install''d copy. Any ideas?

[happycube]

Finally got around to having "make install" stash the git version info into a string. get_git_info() will use the file when the git commands do not work, so presumably it will work in an installed copy.

[happycube]

I think this is fixed now with that commit...