Add AddIns into the Get Functionallity

[peter_michel]

Every Computer change I appreciate the "Get" Funtion for the Preferences. 

I'm missing that the AddIns will be integrated into my preferences. Now I need to install them every time again. It would be helpful to have one Click and have Jmp running as is ran on the old computer.

Thanks Peter

[Craige_Hales]

Also migrate recent files list. I'm quite dependent on the pinned vs unpinned recent files to find anything!