ENH: Add PercutaneousApproachAnalysis extension

Description:
The Percutaneous Approach Analysis is used to calculate and visualize
the accessibility of liver tumor with a percutaneous approach.

Contributors:
Koichiro Murakami (Shiga University of Medical Science, Japan, SPL),
Laurent Chauvin (SPL), Junichi Tokuda (SPL)
Merge pull request #685 from tokjun/add-PercutaneousApproachAnalysis-master

ENH: Add PercutaneousApproachAnalysis extension