Strip trailing whitespaces and normalize line endings

Trailing whitespace do not have impact on the result, they are just
unused bytes. Most text editors are configured to strip trailing
whitespaces. Remove them all in one go.

Update a handful of files to use the UNIX line ending.

tests/test_pycode.py

@@ -26,7 +26,7 @@ def test_ModuleAnalyzer_get_module_source():
         ModuleAnalyzer.get_module_source('builtins')
     with pytest.raises(PycodeError):
         ModuleAnalyzer.get_module_source('itertools')
-        
+
 
 def test_ModuleAnalyzer_for_string():
     analyzer = ModuleAnalyzer.for_string('print("Hello world")', 'module_name')