Argparse

[Jason2605]

Argparse

What's Changed:

This PR updates the Argparse builtin with the following changes:

• Allows negative numbers to be input on addNumber
• Mark user defined usage as optional when creating the Parser object
• Add parser.usage() to docs
• Make any non-required option that is not filled in be null
  • Rationale for this is it will reduce boilerplate of having to .getAttrbibute() rather than just if (!args.<arrg>)
• Mark preArgs and required as instance variables for the (probably very rare) occasion that we want multiple Parser objects
• Display if the argument is required in usage

Type of Change:

• Bug fix
• New feature
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Housekeeping:

• Tests have been updated to reflect the changes done within this PR (if applicable).
• Documentation has been updated to reflect the changes done within this PR (if applicable).

Screenshots (If Applicable):

[briandowns]

LGTM!