Add check that the event number is valid when filling the
EventPrincipal. Also add constants defining invalid event,
lumi and run numbers to the EventID class. Fix a few unit tests
broken by this.
Move constants and typedefs to a separate new file.
Add csa_assert macro.

Just like the normal assert, however it's only enabled when running
in the clang static analyzer. Can be used to guide static analysis
in case of false positives.
Merge pull request #5031 from ktf/fix-add-csa-assert

Add csa_assert macro.
Merge pull request #4858 from wddgit/checkForEvent0

Add check that the event number is valid
Merge remote-tracking branch 'origin/CMSSW_7_2_X' into CMSSW_7_0_X