Warning for vecname(0) could be more helpful

[jdm]

I find it easy to leave out the indexing operator. It would be nice if we could use a heuristic to detect this and display a better warning than the current "mismatched types: expected function or native function but found vec[uint]".

[marijnh]

This will be a non-issue once we move to [] indexing, which should be pretty soon. I don't think extra clever error messages are worth it for this short period.