Add warning system

[PropGit]

This is a reminder for a future task to be performed at an as-of-yet unscheduled time. For now, this is a discussion item only.

Implement a warning system, in addition to the existing error feature, within the compiler. This involves a number of considerations:

• Multiple warnings per compilation need be possible
  • Current system relies on a single fault (error) then exit; this will likely have to be extended
• Warning suppression
  • Ability for user to suppress warnings of certain types (when they know what they are doing and tire of particular warnings)
    • Consider command-line and/or source code features to do this
  • Never completely hide existence of warnings; ie: when any warnings were suppressed during compilation, and final warning indicating that some warnings were suppressed should appear (and that final warning should not be suppressable).
• Should multiple errors be shown (rather than just one)?
  • Not recommended; systems like that often display many errors that are a phantom related directly to the first error.
• Unique message codes (error, warning, info) need be implemented to allow for specific warning suppression by ID rather than requiring that specific symbolic IDs be created for that purpose.