Remove saveOrUpdate from EmailContent to prevent stale writes

  * Numerous classes modified to deal with this change
  * Fixes bugs 1993292 and 1994671
  * Renamed various setter and getter methods to reflect the underlying
    field names
  * Renamed syncFrequency to syncInterval in Account and Mailbox
  * Convenience method added to AccountSettings to save only user settings
  * Calls to content.update(context, content.toContentValues()), which save
    all fields, should be double-checked for correctness, making sure that
    content has current data and will not conflict with other threads that
    might modify that data
  * Ran all unit tests to confirm proper function

NOTE:  The logic to enforce single default account no longer works,
because that logic is in and does not run via
Account.update().  I have patched out a small section of the relevant unit
test and will file a bug to come back for this fix.
5 files changed