Allowing "copy" out of DetailsWindowController

[coffeeshopped]

Hi, I know this pull request is sloppy but I created it just to ask if this feature might be a welcome addition:

I added a very simple way to copy sysex data out of the DetailsWindowController. I've wanted this for a long time in situations where I have a sysex file (e.g. a full synth backup) and I just want to pull a selection of the sysex messages out of it.

This change turns on multiple selection in the table view in DetailsWindowController, and adds a simple copy method. The data is copied to the clip board as a string in the typical hex format, as that seems to be readily paste-able to Hex Fiend, which is where I put the data to create the custom .syx file I want.

I could clean it up more if it's of any interest.

[krevis]

Thank you, not a bad idea! At first glance this seems pretty simple and straightforward.

Things I'll check on:

• Ideally if you select multiple messages, we would show all the data in the hex dump below
• Let's see if we already have code to format each message's data as hex (perhaps expertDataForDisplay() is already the right thing?)
• Look at what HexFiend's view puts on the pasteboard if you copy from the data in the hex dump, and try to do the same thing

[krevis]

(Even better, we might as well add a way to export the selected sysex messages as .syx or .mid. Would just need to add a menu item or button somewhere.)