Create general API for managing persistent game options

[james7132]

This is mainly necessary for having a configurable game. The system needs to meet the following requirements.

• Persistent: these options should be readable
• Reflective: there should be ways to inspect all of the options. This will be particularly useful with auto-generating UI for menus.
• Type-safe

Proposed implementation:

Options will be stored and managed by a OptionsSystem, Supporting a way to access a iterable, categorized list of Option objects.

[Category("Match")]
public class MatchOptions : OptionsBase {
  [Option("Show Damage")]
  public bool ShowDamage { get; set; }
}

[james7132]

Complete with the merging of #71.