Rename getArgumentParser and initArgumentParser methods based on PEP 8.

Closes #51

configargparse.py

@@ -24,10 +24,10 @@
 # global ArgumentParser instances
 _parsers = {}
 
-def initArgumentParser(name=None, **kwargs):
+def init_argument_parser(name=None, **kwargs):
     """Creates a global ArgumentParser instance with the given name,
     passing any args other than "name" to the ArgumentParser constructor.
-    This instance can then be retrieved using getArgumentParser(..)
+    This instance can then be retrieved using get_argument_parser(..)
     """
 
     if name is None:
@@ -43,7 +43,7 @@ def initArgumentParser(name=None, **kwargs):
     _parsers[name] = ArgumentParser(**kwargs)
 
 
-def getArgumentParser(name=None, **kwargs):
+def get_argument_parser(name=None, **kwargs):
     """Returns the global ArgumentParser instance with the given name. The 1st
     time this function is called, a new ArgumentParser instance will be created
     for the given name, and any args other than "name" will be passed on to the
@@ -53,7 +53,7 @@ def getArgumentParser(name=None, **kwargs):
         name = "default"
 
     if len(kwargs) > 0 or name not in _parsers:
-        initArgumentParser(name, **kwargs)
+        init_argument_parser(name, **kwargs)
 
     return _parsers[name]
 
@@ -931,9 +931,15 @@ def already_on_command_line(existing_args_list, potential_command_line_args):
 SUPPRESS = argparse.SUPPRESS
 ZERO_OR_MORE = argparse.ZERO_OR_MORE
 
+# deprecated PEP-8 incompatible API names.
+initArgumentParser = init_argument_parser
+getArgumentParser = get_argument_parser
+getArgParser = get_argument_parser
+getParser = get_argument_parser
+
 # create shorter aliases for the key methods and class names
-getArgParser = getArgumentParser
-getParser = getArgumentParser
+get_arg_parser = get_argument_parser
+get_parser = get_argument_parser
 
 ArgParser = ArgumentParser
 Parser = ArgumentParser