Fix argument-count requirements for runtime-vararg functions.
Only decrement argcount on typesafe variadics.
Throw static assert when non-typesafe variadics are wrapped.
Add unit test for zero-length typesafe variadic calls.
Whoops, forgot va_end on concat_cvar
compute requiredArgs at compile-time
Merge pull request #69 from aubade/master

Fix argument-count requirements for runtime-vararg functions.