MultipoleT now converges for curved magnets
MultipoleT is split into three derived classed and a base class

This reverts commit 69985bb1.

fix compiler warnings for missing declarations: put functions in anonymous namespaces; add header includes

Fixes #56 - OpalRing components throw segmentation fault and #59 - Unit tests throw segmentation fault; partial implementation of #68 DumpEmFields

ParallelTTracker. Particle-Matter interaction doesn't work either at the moment.

I hope that I didn't create too much of a mess when merging!

cleaning up unit tests; make sure to install gtest somewhere and to export the corresponding variable first, there is an install script under tests/tools