Evaluate arguments only once in min/max builtins (fixes #738).
Merge pull request #760 from openscad/slow-min-max-fix

Evaluate arguments only once in min/max builtins (fixes #738).
eliminated duplicate calls to getArgValue() in (most of) builtin functions
add -Wno-unused-local-typedefs option
Merge branch 'unstable' of https://github.com/tim-caper/openscad into unstable