Script Brushes: Function argument errors

[ihm-tswow]

Transferred from tswow#33

• In debug mode, default arguments do not seem to work.
  Note: Has likely been resolved since 330c323

• In release mode (msvc only, it seems), incorrect arguments are accepted to functions.
  Note: Can likely be fixed by enabling this: Binding functions with default parameters ThePhD/sol2#340 (comment)