Use VERSION.py instead of plain VERSION

reduce dependence on package_data

gridlock/VERSION

@@ -1 +0,0 @@
-0.4

gridlock/VERSION.py

@@ -0,0 +1,4 @@
+""" VERSION defintion. THIS FILE IS MANUALLY PARSED BY setup.py and REQUIRES A SPECIFIC FORMAT """
+__version__ = '''
+0.4
+'''

gridlock/__init__.py

@@ -15,15 +15,11 @@ Dependencies:
 - mpl_toolkits.mplot3d  [Grid.visualize_isosurface()]
 - skimage               [Grid.visualize_isosurface()]
 """
-
-import pathlib
-
 from .error import GridError
 from .direction import Direction
 from .grid import Grid
 
 __author__ = 'Jan Petykiewicz'
 
-with open(pathlib.Path(__file__).parent / 'VERSION', 'r') as f:
-    __version__ = f.read().strip()
+from .VERSION import __version__
 version = __version__