Speeds in kilobits or kibibytes per second

[narcisgarcia]

My proposal is to indicate everywhere the unit in use: kbps or KiB/s. (kb/s is a confusing notation)
This means speed preferences form, and documentation page:
https://transmissionbt.com/help/gtk/2.9 ... ences.html

+ I propose this unit to be configurable with an additional preference: Units: [Dropdown]