* initial password key derivation design
* some typos/clarifications
* point out that clients can ignore bucket entropy
* clarification about offline table generation
* change proposal to only do network requests when inputting passwords
* make algorithm have shorter lines
* fix algorithm example
* be explicit about allowing already-formed root keys
* go back to having a salt in the project/bucket metadata
* some proofreading/clarifications
* feedback and clarifications
* clarify definition of root key
