* Review PDD 19 PIR for namespaces behavior * Review PDD 21 Namespaces * TT #389 - don't install subs with :method into NameSpaces * Review src/global.c:

• Too many lookup functions may return NULL, which is inappropriate when exposed to PIR
• PMCNULL is more appropriate for "Element does not exist"; it's used elsewhere pervasively
• Parrot_set_global(), for example, is unsafe, considering its signature
• There's a mixture of internal and external APIs
• We should create an api.c file for symbols, namespaces, whatever