Create simple version of insertAsm() that takes no in/outputs

The distribution's release version failed due to disabled assertions.
The problem was that if there are no return values from an inline
assembly call, we cannot simply return an empty array (as we formerly
did), but must return a void type.

As a consequence, there is now a simple version of insertAsm() that
builds an InlineAsm function type that takes no in/outputs, and
constructs the function call as such (and makes the assertions remain
silent).

As a side note, a check has been added to the generic insertAsm() method
that should (theoretically) do the same thing. Currently this has not
been tested, due to method overloading (the case of omitted in/output
arguments is no longer accepted, as it is now being handled by the
simple insertAsm() method).
I'll run some tests to see whether it resolves the issue, and then
technically we would no longer need the simple insertAsm() (which I
personally consider a hack).