Timestamp for begin and end of a transmission for a file

Actually the time-stamp of a transmission reflects the time of end-of-transmission only.

This mus be changed by using 'two time-stamps. One for the start and the second for the end-of-transmission. This must be implemented on the file-basis for every single file. On the "order"(an order is the execution of a specific profile) for the start and end of the transmission for all files.

What has to be changed/extended:

1) Client: get start and end-time for every file
2) Client: calculate start and ent-time for an order

2a) Client/Standard-Job: extend the JS-Order with a new parameter (start_timestamp)

3) database: add new field
4) Standard-Job: process the new parameter

5) SOSFtpGUI: include the new file in the visible columns-list