Practical guide to app architecture

[mattyg]

Must include:

• code examples
• practical, terse explanation of how to use
• gotchas

Possible topics include

• Composing zomes and DNAs into an app
  * DNA and app manifest formats
  * Coordinator swapping
  * cell provisioning strategies
  * Create -- always create a new cell
  * UseExisting -- requires existing cell under same key derivation tree (not implemented?)
  * CreateIfNotExists -- try UseExisting followed by Create (not implemented?)
  * CloneOnly -- defer instantiation until first clone. How is this different from Create with deferred and no effective instantiation?
  * Common flags
  * deferred -- don't create one until asked (not implemented? how do you ask?)
  * clone_limit -- how many clones can be created?