Detail and test exceptions

[bigbigant]

exceptions: Lex, Parse, Compile(After...),Runtime...

[bigbigant]

+ Tage\Exception
 | + Tage\Compiler\Exception
 |  | Tage\Compiler\LexerException
 |  | Tage\Compiler\ParseException
 |  | Tage\Compiler\CompilingException
 |  | Tage\Compiler\ValidationException
 \ + Tage\Runtime\Exception
    | Tage\Runtime\IoException fail to operate fs or other storages
    \Tage\Runtime\UserException  $context->fail() is invoked

+ Tage\Runtime\Signal  可预期的控制信号，用于提前结束模板渲染
 |  Tage\Runtime\LocalStopSignal
 |  Tage\Runtime\LocalSkipSignal
 |  Tage\Runtime\StopSignal
  \ Tage\Runtime\SkipSignal