Use setuptools_scm for versioning

Automatically generates the `usb.__version__` string on installation.

Closes #298.

.gitignore

@@ -5,3 +5,4 @@ MANIFEST
 dist
 .tox
 *.egg-info
+usb/_version.py

pyproject.toml

@@ -0,0 +1,2 @@
+[build-system]
+requires = ["setuptools>=30.3.0", "wheel", "setuptools_scm"]

setup.cfg

@@ -1,2 +1,5 @@
 [metadata]
 description-file = README.rst
+
+[options]
+setup_requires = setuptools_scm

setup.py

@@ -32,12 +32,13 @@
 
 from setuptools import setup
 
-import usb
-
 
 setup(
     name='pyusb',
-    version=usb.__version__,
+    use_scm_version={
+        "version_scheme": "post-release",
+        "write_to": "usb/_version.py",
+    },
     description='Python USB access module',
     author='Robert Wlodarczyk',
     author_email='robert@simplicityguy.com',

usb/__init__.py

@@ -48,8 +48,19 @@
 __author__ = 'Wander Lairson Costa'
 
 # Use Semantic Versioning, http://semver.org/
-version_info = (1, 0, 2)
-__version__ = '%d.%d.%d' % version_info
+try:
+    from usb._version import version as __version__
+except ImportError:
+    __version__ = '0.0.0'
+
+def _get_version_info(version):
+    import re
+    m = re.match(r'(\d+)\.(\d+)\.(\d+)[.-]?(\D.*)?', version)
+    return tuple(
+        int(v) if v.isdigit() else v for v in m.groups() if v
+    )
+
+version_info = _get_version_info(__version__)
 
 __all__ = ['legacy', 'control', 'core', 'backend', 'util', 'libloader']