Modifying DecorateImmediate to enhance diagnostics

This routine cannot be called with zero arguments, anyway, and rather than a cryptic "zero sized array" error message, instead users will see that they are calling the function with the wrong number of arguments.
Fixes #19

Cause was a torn refactor when the unit tests were reshuffled to use test filters instead of a universal artifical base
Correcting invalid linker flag for clang on other platforms
Merge pull request #21 from leapmotion/ref-decorateimmediate

Modifying DecorateImmediate to enhance diagnostics
Merge pull request #22 from leapmotion/issue-20

Correcting invalid linker flag for clang on other platforms