::Runtime -- Run a TestML Function

    The TestML Code and Data get compiled into a Function, and the Function
    is run by this Runtime class. Typically data is manipulated by Bridge
    functions, and at some point Assertions are made. The assertions are the
    things that call Test::More::is and Test::More::ok.

    ::Compiler -- Turn a TestML document into a runnable TestML Function.

    A TestML "document" is comprised of 3 main parts: Meta, Code, Data. This
    information often is in a single TestML (.tml) file or string, but it
    doesn't need to be. The information can come from anywhere and be in any
    form that is supported; it just must all be present when it is needed.

    The Meta information must be known first. It dictates where the Code and
    Data come from, and in what format they are. Also the Code and Data
    formats depend on the TestML API Version that is supplied. Before the
    Code and Data can be compiled, a Version must be supplied (no default)
    and then the compiler must support that Version. This allows TestML to
    change over time with no confusion.

    The compile function returns a Function object, which in turn contains
    an array of Statements and an array of Data Blocks. This function is the
    run by the Runtime object.

    A Function is just an array of "executable" statements that are
    proceseded in order. Some of the statements maybe be function
    declarations and function calls. The Compiler produces a top level scope
    function, with a Data set, and a Namespace for variables.

    All functions are anonymous, but they can be assigned to variables, and
    then you can call that variable name.