Fixup `call` operations to deal with lack of tail calls
Fixes issue #76
Mark test_checked_procedure_check_and_extract and test_struct_prop_arity as failing
Making calls work properly breaks these functions
Merge branch 'master' into structs
fix test_checked_procedure_check_and_extract, replace W_CallableStruct by W_Struct (with optional call method), test_procedure skipped because it's the implementation was wrong