FPE handling in CA-based jobs

With this MR, a new flag Exec.FPE controls how Floating Point Exceptions are handled in ComponentAccumulator based jobs. A value of -1 is the equivalent of the old-style flag "rec.doFloatingPointException=True", eg the job will be aborted with a core-dump on the first FPE. A value of 0 (default) will set up the FPEAuditor to print a one-line WARNING on each FPE, like the standard behavior with RecExCommon. A value greater then 0 will set the property FPEAuditor.NStacktracesOnFPE to this value, eg stack-traces will be printed for that many FPEs.

While working on this, I realized that Auditors were no properly handled by the ComponentAccumulator. The first commit fixes this issue.