When marking a message, a race condition can happen:
- A remote folders update is already running
- We mark the message locally and replay it remotely
- The previous remote update result restores invalid values locally
Adds classes that allow building arbitrary query expressions and require
an instance to be provided to Geary.SearchQuery, to be set as a
property.
This enables query expressions to be parsed by clients instead of the
engine, in which ever whay they choose.
Support API clients registering their own local folder implementations.
Use this (and the last commit) to generalise handling of the outbox by
GenericAccount by registering it when the outbox postie is started, and
when creating a map of folders that contain specific ids.
This also ensures API clients are informed of the outbox becoming
available, allowing some special case code to be removed from the app
controller.
Add new public method that allows API clients to query whether a folder
contains a specific set of email ids. Add implementation to all
derived classes.
Engine mocks don't need to be in the `Geary` namespace, and including
them there makes it difficult to use them in client tests, so put them
all in their own name-space and corresponding directory.
