Fix relative imports under Python 3

[heubi95]

When running test_ranges.py under PyCharms, the following exception occurs:

Traceback (most recent call last): File "C:\Program Files (x86)\JetBrains\PyCharm Community Edition 3.4.1\helpers\pycharm\utrunner.py", line 135, in module = loadSource(a[0]) File "C:\Program Files (x86)\JetBrains\PyCharm Community Edition 3.4.1\helpers\pycharm\utrunner.py", line 40, in loadSource module = imp.load_source(moduleName, fileName) File "C:\Python34\lib\imp.py", line 171, in load_source module = methods.load() File "", line 1220, in load File "", line 1200, in _load_unlocked File "", line 1129, in _exec File "", line 1471, in exec_module File "", line 321, in _call_with_frames_removed File "C:\Users\Heubi\Documents\GitHub\cutplace\cutplace\test_ranges.py", line 19, in from . import ranges SystemError: Parent module '' not loaded, cannot perform relative import

[roskakori]

According to http://stackoverflow.com/questions/16981921/python-3-relative-imports, importing from "." only seems to work properly if the application / test case is run using python -m .... As this is not the case when running them from the IDE (e.g. PyCharms), ImportErrors ensue.

The reason why it still worked on my machine was because I added the cutplace folder to PYTHONPATH a long time ago.

So the current workaround of using from cutplace import ... actually is the proper solution to this issue.