Release 0.5.4 (2017-08-14)

• Trying to make tests more stable wrt breakpoint columns.
• Return only distinct locations when setting a breakpoint.
• Parse ES6 arrow functions when guessing columns.
• Properly pause on uncaught exceptions (issue #52)
• Fix variable setting when stack contains recusion (issue #53)
• Emit Runtime.exceptionThrown for uncaught errors.
• Support marshalling of ES6 Symbol (Java 9) (issue #54)
• Support marshalling of ES6 Map, Set, WeakMap and WeakSet (Java 9) (issue #56)
• Stability fixes
• Marshal __proto__ correctly