Added TryCatchException to catch custom errors
Added tests for TryCatchException
Update a comment
Added ThrowException2 to throw Value
Added a test for ThrowException2
Added factory methods of exceptions
Added a test for exceptions
Fixed a cast mistake
Changed variadic function bind to support preceding fixed arguments
Added a test for variadic function bind
Merge pull request #25 from fukuchidaisuke/exception

Support custom errors
Merge pull request #27 from fukuchidaisuke/throw

Throwing Value support
Merge pull request #28 from fukuchidaisuke/variadic

Change variadic function bind to support preceding fixed arguments