Add partial support for metavariables in the normalizer

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
Update .travis.yml

fix typo [skip ci]
Update src/CmakeLists.txt - only check style over files starting with [A-z]
Fix memcheck.supp problem
Use unsigned short for the type of interval::bound_deps
Add static assertion to util/safe_arith.cpp
Fix typo in .travis.yml