UNUSED(arg) amcros are now detected in pmc bodies and change the argument declaration
Empty bodies with return 1; are now detected and the two args are SHIMed.
UNUSED(interp) cause a new warning to be replaced by UNUSED(INTERP).
support multiple shim'able parameters
warns on not SHIM'ed parameters, possibly internal unused variables
warns on possibly forgotten UNUSED(param) declarations
warns on an possible internal recursion error, when the UNUSED decl could not be replaced
skips SHIM'ing method bodies with #if
detect empty bodies and adds SHIM'ed INTERP and SELF params automatically