* fixed handling of incomplete char/string literals in `isPrefixStringCharLiteral()` - also optimized it a bit / added tests for `isStringLiteral()` and `isCharLiteral()`
* utils.h: early out in `isStringCharLiteral()` to avoid the loop
* fixed functionConst findings and enabled it in selfcheck
* fixed functionStatic findings and enabled it in selfcheck
* .travis_suppressions: adjusted comment
* testimportproject.cpp: added missing asserts