Changes from 1.16.2 to 1.16.3

• Fix for building for clang with -march=haswell. See PR #262.

• Fix all the known warnings for GCC/Clang. Still some work to do for MSVC
  in this front.

• Due to some problems with several CI systems, the check for library symbols
  are deactivated now by default. If you want to enforce this check, use:
  cmake .. -DDEACTIVATE_SYMBOLS_CHECK=ON to re-activate it.