* mailserver sends envelopes in descending order
* add limit value in mailserver request payload
* mailserver sends messages up to the limit specified in the request
* update Archive method to return key and error
* processRequest returns the next page cursor
* add cursor to mailserver request
* add limit and cursor to request payload
* fix request limit encoding
* wait for request completed event in TrackerSuite/TestRequestCompleted
* add cursor to mailserver response
* fix cursor position in payload
* add e2e test for mail server pagination
* validate mail server response size
* remove old limitReached var
* fix lint warnings
* add whisper patch
* fix tests after rebase
* check all return values to avoid lint warnings
* check that all messages have been retrieved after 2 paginated requests
* fix lint warnings
* rename geth patch
* merge mailserver patches into one
* add last envelope hash to mailserver response and EventEnvelopeAvailable event
* update whisper patch
* add docs to MailServerResponse
* update whisper patch
* fix tests and lint warnings
* send mailserver response data on EventMailServerRequestCompleted signal
* update tracker tests
* optimise pagination test waiting for mailserver to archive only before requesting
* rollback mailserver interface changes
* refactoring and docs changes
* fix payload size check to determine if a limit is specified
* add more docs to the processRequest method
* add constants for request payload field lengths
* add const noLimits to specify that limit=0 means no limits
Andrea Franz