Options - Auto Changing Simultaneous Transfers

[Nate15329]

Adding the optional option for FileZilla to change Simultaneous transfers based on current file size(user set) that is currently being transferred.

Example: User sets if a file is greater than or equal to 1GB(customizable) use only x(customizable) simultaneous transfer in transfer options when enabling this optional option by checkbox. While the norm of that user is using x simultaneous transfers. (x=1<->10)

Basically smaller files get multiple transfers while larger files run on a single or few transfer/s to speed up the transfer of the larger files since the current bottleneck for the larger files would be the network and disk speed.