added akima support to csg_resample
added akima support to csg_resample

new review:
owner: victor.ruehle
cc: christoph.junghans, sebastianfritsch1983
summary: review akima stuff
branch: akima

richardjgowers/csg,richardjgowers/csg,richardjgowers/csg,richardjgowers/csg,richardjgowers/csg