Simplify the two-loop results and evaluate the Zeta functions
Bugfix: two-loop QCD bits:
 * correct log term in bottom contribution
 * Numerically evaluate as much as possible
 * Dynamically check for particle symbol name at runtime,
   because SARAH might set the name after the TwoLoop` module
   was loaded
Prepare DRbar mass routine for the two-loop QCD corrections
Add getters to access information that was stored in the exceptions.
Add helper function FiniteLog() which avoids Nan
forgot inline keyword
Add error class for tachyons
Add helper function which checks for Nans in DoubleVector
Make sure that Log() is not called with negative argument and
make sure that Log(0) will return 0 to avoid infs.
Check for tachyons in the scalar and vector boson sector at tree-level
Temporarily print a warning only if we have a tachyon.