Feature: Measurement Files Interchangable Between Imperial and Metric

[GraceDM]

Describe the new feature you would like to see in Seamly

I need to be able to load an Imperial measurement file into a pattern created using Metric measurements and vice versa.

So the software in Seamly2D needs to check whether the SeamlyME file is Imperial or Metric and convert the measurements to the system used while drafting the pattern.

I also need to be able to create both Imperial and Metric multisize measurement charts.