[no immediate action required] Package maintainers: please check your dependencies!

Dear downstream package maintainers,

I just checked the homebrew GNU Radio packaging, and found the (as of v3.10.11.0) no
longer used dependency of python click-plugins in there. That's no big deal (probably),
but it's not the only dependency we've worked on in the last couple years.

So, please feel invited to check whether what GNU Radio depends on is actually not less
than what your package depends on. Especially, we removed:

- Qt4
- libcomedi
- a lot of Boost components we used to depend on (currently I think we're still using
date_time, program_options, system, thread, not sure that's exhaustive; anyways,
everybody's boost packaging is different)
- log4cpp

we added (not exhaustive list) for some optional features

- libsndfile
- libsoapysdr
- (if you want blocktool) pygccxml
- (if you want blocktool and the config blocks) python-jsonschema

If you want to have an overview of the libraries for which we give minimum versions,
cmake/Modules/GrMinReq.cmake is our centralized place where we keep these around.

If in doubt, raise hell :)

Cheers,
Marcus