Changed data that is saved and save file format

2 main parts changed:
a) Saving of size of preview windows.
Why? Because I have 5 clients running, 2 with larger previews than the others. Software did only save the location, but reset the size on restart

b) Changed save file format (still XML)
Why? Because with "unique layout" checked it did save XML with multiple same tagnames in different depths of XML.
And I added support for the machine name, because I use different setups on different PCs with different amount of monitors and resolutions - but I share the same config file via SVN.

I DON'T KNOW IF THIS IS THE RIGHT WAY TO GET THE CHANGES TO YOU! ;D
Message me if not, I'm using GitHub the first time