Improve Python 3 compatibility

Mostly adding relative imports.

src/nxpeaks/__init__.py

@@ -5,14 +5,15 @@
 #
 # The full license is in the file COPYING, distributed with this software.
 #-----------------------------------------------------------------------------
+from __future__ import absolute_import
 
 __package_name__ = u'NXpeaks'
 from ._version import get_versions
 __version__ = get_versions()['version']
 del get_versions
 
 __documentation_author__ = u'Ray Osborn'
-__documentation_copyright__ = u'2013-15, Ray Osborn'
+__documentation_copyright__ = u'2013-16, Ray Osborn'
 
 __license__ = u'BSD'
 __author_name__ = u'NeXpy Development Team'

src/nxpeaks/blobcorrector.py

@@ -28,7 +28,8 @@
 To think about doing - valid regions? What if someone uses a 1K spline
 file for a 2K image etc?
 """
-import logging, numpy, math
+from __future__ import absolute_import
+from . import logging, numpy, math
 from scipy.interpolate import bisplev
 
 def readfit2dfloats(filep, nfl):

src/nxpeaks/nxrefine.py

@@ -1,10 +1,13 @@
+from __future__ import absolute_import
+
 import numpy as np
 import os
 import random
 from scipy.optimize import minimize
+
 from nexusformat.nexus import *
-from nxpeaks.unitcell import unitcell
-from nxpeaks import closest
+from .unitcell import unitcell
+from . import closest
 
 
 degrees = 180.0 / np.pi