* Review ModestProgressBarWidge, adding a GtkAlignment and

* Review ModestProgressBarWidge, adding a GtkAlignment and
GtkAdjustment.
* Fix bug on GB potfile in "Sending %d/%d1" message.
* New operation mail_operation_process_msg, to get one or several
messages, applying them an user define function, using a
helper data structure to do this.
* Change tny_get_msg_async calls in modest-ui_actions
by a new mail_operation method called mail_operation_process_msg.
* Add a new method to ModestPropressObject to cancel current
mail operation in progress.
* Connect ModestMainWindow as observer of MailOperatinQueue, to
add and remove mail operations from their observer.
* Connect ModestMsgViewWindow as observer of MailOperatinQueue, to
add and remove mail operations from their observer.
* Manage toolbar of MsgViewWindow, dimming toolbar options
in transfer mode.

pmo-trunk-r1738