Implement Inline Methods

I've decided that we will pursue implementing this on top of our existing method syntax. The rules are simple, but might require some complex brain work to get the parser ready and capable of parsing the additional rule. The purpose of inline methods is to prevent the need to round trip results to variables and increasing the number of lines of code to parse and execute, costing time and energy, of which we have limited amounts of both.

Basically, it works as follows: if the input parameter in a method begins with $, @, [, ", or ', then that parameter is an expression and should be parsed as such. Otherwise, treat the parameter as the preferred variable type.

As Expression

let lines = @lines($read("filename"))
let lines = @lines($(cmd args...))
let lines = @lines($string_var)

As Variable

let lines = @lines(string_var)