Build a parser

[amg-12]

It would be nice to have a parser to parse the arguments of /scriptevent commands. The parser would take string representations of the types supported by MakeCode (number, position, selector) and parse them into the corresponding ScriptAPI types (number, Vector3, EntityQueryOptions). Without a parser, I have to use hacks which cost in readability and probably performance.

[amg-12]

Upon discovering mobs.queryTarget(), parsing target selectors will no longer be necessary. I can query the target's unique ID, and pass that as an argument in place of a selector string.