Consider allowing functions to be defined at the byte code level

[thelonious]

Right now, functions are 'built' in the em parser and ema assemblers. We already have concepts like symbols and blocks that can be manipulated at the byte code level. However, we're missing support for defining parameter lists and default values. Now that object values are ordered dictionaries, we should be able to define those with objects. The byte code might look like:

{[ x 10 y 20 z undefined]}
{ <function-body-here> }
createFunction

This would result in a function-value on the stack which could then be assigned to a symbol