Add an event listener to the parser. Once the event firesoccurs, theparser will call the associated function will be called, which will and pass in a referenceto itself. The parser needs to pass itself. This way back to the library since the library knows which parser it is could be working withmany parsers simultaneously.

@param {String} eventName - can beone of the following: "onstart" - must occur exactly once - func(parser) "onparse" - must occur one or many times - func(parser, {"VERTEX":[...], "COLOR":[...], etc...} "onfinish" - must occur exactly once - func(parser)

@param {Function} func - the function to call when the event occurs.

@param {String} path - Path path to resource