Add packaging infrastructure

Split up single script into a package with multiple modules.
Also add a setuptools control file. With this, stcgal can be
installed like any other program. It's still possible to launch
from the sources directly. stcgal.py has been converted into a
simple launcher.

v2: fix imports

setup.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python3
+
+import stcgal
+from setuptools import setup, find_packages
+
+setup(
+    name = "stcgal",
+    version = "1.0",
+    packages = find_packages(exclude=["doc"]),
+    install_requires = ["pyserial"],
+    entry_points = {
+        "console_scripts": [
+            "stcgal = stcgal.frontend:cli",
+        ],
+    }
+)