TileConditions: Fix clang compilation and warnings.

clang compilation:
 - Need to put explicit instantiation of TileCalibData specializations after all
   member template definitions; that is, at the end of TileCalibData.cxx rather
   than in TileCalibData.h.  Otherwise, clang doesn't instantiate those members.

clang warnings:
 - Missing override keywords.
 - Unused variables and private class members.


Former-commit-id: 52bf7f33