py: Simplify "and" action within parser by making ident-rules explicit.
Most grammar rules can optimise to the identity if they only have a single argument, saving a lot of RAM building the parse tree. Previous to this patch, whether a given grammar rule could be optimised was defined (mostly implicitly) by a complicated set of logic rules. With this patch the definition is always specified explicitly by using "and_ident" in the rule definition in the grammar. This simplifies the logic of the parser, making it a bit smaller and faster. RAM usage in unaffected.