Update clang static analyzer to version 6

Update clang static analyzer to version 6

Corrected the comment about how prepare to run such a job.

Fixed check_cons. With econqVeloc, different quantities get passed
into x, and nullptr into v, so the diagnostic output was always wrong
if the run found issues while doing velocity constraining.

Simplified the implementation of SIMD setZero() proxy object.

Added lots of const and some assertions for DD communication code.

Also fixed some complaints from MSVC about bool

Change-Id: Idb741480544189b68db78be57167e3f4ce577bd7