The Sigils library will now only be compiled in and able to convert
math structures if the convert_sigils feature is selected.
use_std would have also been set as a feature, but the library heavily
uses std::collections::vec::Vec. Until a non-std version of a collection
has been written, then this needs to be used.
This tests buffer overflow for the basic types. It does not currently
test the platform int and uint until the final function definitions
are determined.
