…tiple different Null objects is not a good idea because PMC_IS_NULL will only catch x == PMCNULL, not isa(x, 'Null')
… a Null PMC. Fix another test that expected Null to be a singleton type
…y matching on the exact text of the exception message, which is changing for GH #759
…er to file a bug report. A few small cleanups
…re declared in string_funcs.h instead of misc.h. Change the sprintf engine to use a StringBuilder instead of repeated (wasteful) string concats.
…ot_api_pmc_new_call_object and Parrot_api_pmc_setup_signature
…for constructing a CallContext from a signature string and a variadic argument list. brrt++ for the suggestion
…call_object. Use that in the new_call_context op. Also, expose it through a convenient new Parrot_api_new_call_object API function. brrt++ for the suggestion