v0.4.2

This release includes several one feature and several bug fixes.
Feature:

1. if_succeds annotations are now allowed on contract definitions. They are automatically applied to all public/view non-pure functions in this contract, and all inheriting contracts.

Bug fixes:

1. Exception thrown when calling annotated functions from another annotation (#36)
2. Spurious syntax error on docstring that contain the 'define' word at the begining of a line (#28)
3. External view function calls not transpiled correctly (#27)