Fix up Volk versioning info: readying for release of 1.0.0

Remove vestiges of reliance on GNURadio repo
GrPython -> VolkPython
Minor fixups in lib/CMakeLists.txt
Update copyright on all files
build: more mods for installation and versioning.

- Fixes the version info in the .pc file so pkg-config --moderversion returns the correct result.

- Adds a VolkConfigVersion.cmake to allow find_package(Volk [version]) for the major, api, and minor version compatibility.
build: remove unused variable in cmake config install
bring over gitignore from GNU Radio