Define procedure for Feature Proposals

[sam]

Should write up a Wiki article describing how we get from idea to delivered feature. ie:

• Add Issue to discuss feature
• Add Wiki page documenting feature as Pending
• Write tests (and revise Wiki as necessary as requirements evolve)
• Write implementation (and revise Wiki as necessary)
• Thoroughly comment implementation and tests, referencing Issue and Wiki

Something like that. We need to make documentation a high priority.