Add visitEmitStatement method

Allows parsing of event emit statements.
Uses the same nomenclature as Solidity ast-compact-json.

Author: noitatum

solidity_parser/parser.py

@@ -313,6 +313,11 @@ def visitFunctionCall(self, ctx):
                     arguments=args,
                     names=names)
 
+    def visitEmitStatement(self, ctx):
+        return Node(ctx=ctx,
+                    type='EmitStatement',
+                    eventCall=self.visit(ctx.getChild(1)))
+
     def visitStructDefinition(self, ctx):
         return Node(ctx=ctx,
                     type='StructDefinition',