Add ability to set per binding metaattrs

[ltaylor16]

- decl: void simple(int i)
  bind:
    f:
      decl:  (arg1 +attr, arg2+attr+attr2(34+43))  +attr
      attrs:
        +result:
          foo: 1
        arg1:
          bar: 2

Use the deref attribute to lookup statements for C wrappers.

Added tests for std::vectors C wrappers which will copy vector results to an array argument or malloc new memory.