add a new line
fix Maint.refresh()
add Maint event listeners
reimplement request_code() with state
correct uri -> url
Agent: enhance session/state management
Client: remove generate_default_state()
TabClient: renamed from Agent
panel: enhance ui a bit
TokenKeeper: renamed from Maint
Client: support response_type 'token'
GoogleOAuth2: absorb some constants
renamed oauthman