Base class for FuzzyOverlap misc tool

Some details are still to be fixed
Working version
Added inputs&outputs descriptions

PR #622
Added new interface for mesh/contour handling

Added base code, just for computing node-to-node distanced.
Some other computations could be added here.
Fix: input_spec and output_spec were not set

Fixed bug in surface-to-surface distance computation.
Implementation of surface weighting

Also fixed total weight normalization
Fixed bug

Input parameter name was used wrongly
Merge remote-tracking branch 'origin/enh/MeshAlgorithm' into enh/MeshAlgorithm
Working version

Checked that works with vtk files. Also checked for consistency when
using the same surface twice.
Run autopep8 on misc.py

In-place run of the standard tool. Ref #662
PEP8 for the whole interface

Fixed all errors. #622
Added dummy files so doctest doesn't fail

Files added in response of https://github.com/nipy/nipype/pull/622#discussion_r5921360
Fixed filenames in documentation

Minor change, as the names were not descriptive.
Merge branch 'enh/MeshAlgorithm' into enh/RSTK
Merge branch 'enh/FuzzyOverlap' into enh/RSTK