* Refactored the code o modest_mail_operation_get_msg and modest_mail_operation_get_...

	* Refactored the code o modest_mail_operation_get_msg and modest_mail_operation_get_msgs_full, now both of them use the same helpers and status callbacks
	* Refactored the notification of mail operations that issue progress notifications in bytes (transfers and gets)
	* modest_mail_operation_get_msgs_full now it's not implemented in a separate thread
	* Fixes NB#75909, retrieve contents now asks for connection if not available
	* Fixes NB#75801, Cancel sending, now really cancels the sending of messages

pmo-trunk-r3730