Various micro-optimisations resulting in approximately ~2.4x performance improvement.

Version 1:

    Icecave\Duct\EventedParserEvent
        Method Name   Iterations    Average Time      Ops/second
        -----------  ------------  --------------    -------------
        parseBuffer: [10        ] [0.1276811838150] [7.83201]
        parseStream: [10        ] [0.1286560535431] [7.77266]

    Icecave\Duct\ParserEvent
        Method Name   Iterations    Average Time      Ops/second
        -----------  ------------  --------------    -------------
        parseBuffer: [10        ] [0.1284358024597] [7.78599]
        parseStream: [10        ] [0.1233790874481] [8.10510]

Version 2:

    Icecave\Duct\EventedParserEvent
        Method Name   Iterations    Average Time      Ops/second
        -----------  ------------  --------------    -------------
        parseBuffer: [10        ] [0.0564356803894] [17.71929]
        parseStream: [10        ] [0.0533864974976] [18.73133]

    Icecave\Duct\ParserEvent
        Method Name   Iterations    Average Time      Ops/second
        -----------  ------------  --------------    -------------
        parseBuffer: [10        ] [0.0545754432678] [18.32326]
        parseStream: [10        ] [0.0537288904190] [18.61196]