move dependencies to extras

setup.py

@@ -74,7 +74,7 @@ setup(
     # your project is installed. For an analysis of "install_requires" vs pip's
     # requirements files see:
     # https://packaging.python.org/en/latest/requirements.html
-    install_requires=["numpy", "argparse", "pyzmq", "pyrtlsdr"],
+    install_requires=["numpy"],
     # List additional groups of dependencies here (e.g. development
     # dependencies). You can install these using the following syntax,
     # for example:
@@ -83,6 +83,7 @@ setup(
     #     'dev': ['check-manifest'],
     #     'test': ['coverage'],
     # },
+    extras_require={"all": ["argparse", "pyzmq", "pyrtlsdr"]},
     # If there are data files included in your packages that need to be
     # installed, specify them here.  If using Python 2.6 or less, then these
     # have to be included in MANIFEST.in as well.