sorted out test cases
move and rename to parse_path in anyconfig.parser from anyconfig.getset.__parse_path_exp
add test cases for anyconfig.parser.parse_path
merge functions from anyconfig.getset to anyconfig.mergeabledict
do not import anyconfig.getset which will be deprecated (its functions are moved into anyconfig.mergeabledict)
deprecated and removed anyconfig.getset
removed anyconfig.mergeabledict._get_recur, recursive version of item
getter for nested dicts, because it's very slow compared to
anyconfig.mergeabledict._get_reduce.

    In [96]: setup = """
    ....: import anyconfig.getset as AGS
    ....: lchrs = [chr(n) for n in range(97, 123)]
    ....: d = AGS._mk_nested_dic('.'.join(lchrs), 10)
    ....: """

    In [97]: timeit.timeit("AGS._get_recur(d, lchrs)", setup)
    Out[97]: 17.171975135803223

    In [98]: timeit.timeit("AGS._get_reduce(d, lchrs)", setup)
    Out[98]: 1.5136559009552002
fuse anyconfig.mergeabledict.{_get_reduce,get} into one and make error messages propagated from anyconfig.mergeabledict.get
follow internal API changes in anyconfig.mergeabledict.get