0.3.0

Breaking

• EvalErrorKind::InvalidBuiltInFuncArgType has been renamed to
  EvalErrorKind::InvalidStdFuncArgType.
• New variants have been added to EvalErrorKind.
• New variants have been added to EvalStackTraceItem.
• ExpectedThing as been renamed to ExpectedToken.
• ParseError::Expected now uses ActualToken instead of TokenKind.
• Arena allocation is now used for interned strings, AST and some internal data
  of Program.
• String interner cannot be garbage-collected anymore.

Fixed

• Reject tags in object keys in std.parseYaml.
• Avoid some panics in std.parseYaml with some inputs found with fuzzing.
• Avoid stack overflow when dropping expressions with too much nesting.

Changed

• Improved error message when passing a value of invalid type to a built-in function.
• Stack trace improvements.
• Performance improvements.