Issues related to Clause 12

[everythingfunctional]

• Add a statement somewhere that "An entity of deferred type shall not appear in a namelist"
• Add a statement somewhere that "An entity of deferred type shall not appear as an input item in a READ statement, nor as an output item in either a WRITE or PRINT statement"

We might be able to say "unless a an appropriate procedure has been added to the appropriate user defined IO generic identifier", but we may need to think hard about it to get it right.