cppcheck fixes (code quality)

These are a set of (mostly trivial) fixes to cppcheck warnings. A few real (although unlikely) bugs were caught. There are still a few non-trivial ones remaining that would need to be addressed separately.

To reproduce (after cmake config):

cppcheck --quiet --inline-suppr --check-level=exhaustive --template=gcc --enable=warning,portability --library=boost --suppress=duplInheritedMember --suppress=invalidscanf --suppress=syntaxError --suppress=unknownMacro --project=compile_commands.json