Major fixes

* Added @tags parsing to PawnComment
* Added more useful __toString methods
* Added PawnDefinition::getValue
* Fixed #pragma incorrectly parsing the next line
* Fixed const not being parsed when function argument does not have a
type
* Fixed functag not being parsed from function types
* Fixed function body parsing
* Fixed last comment not always matching function
* Fixed numbers not being allowed in functions
* Fixed spaces around equal sign after function arguments not being
ignored
* Implemented Serializable
* Refactored PawnFunction::GetArguments to support commas in default
values