Add doc URL Filtering (URL Sandbox)

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Load fallback icon in StatusIcon

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Render number to tray icon pixbuf

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Update action enabled flags with cache

Actions.updateEnabledFlag uses cache of action enabled flags to update
them only if necessary.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>
Update action states with cache

Actions.updateState uses cache of action states to update them only if
necessary.

Signed-off-by: Jiří Janoušek <janousek.jiri@gmail.com>