Add workaround for layout persistance issues with macro frames

[Irarara]

Fixes #2485. As detailed in the discussion around the issue, the layout information for frames that are not added to the DockingManager before layout is loaded is not retained. This works around that by saving the names of macro frames to a file (frames.dat, just a NULL delimited list of the names) when Maptool exits and then, when launching, using those names to generate placeholder frames before the layout is loaded so that the layout information is retained. Really, I'd consider this more of a "temporary" workaround to be removed if the issue is ever actually addressed within the library.

In my testing, it seems to do the trick, layout seems to restore the same as you'd expect pre-1.8, and I also haven't observed any issue with the encoding of the frame names. I did once observe frames opening incorrectly (they opened docked somewhere I know I hadn't put them, and when opening them in 1.7 they were in the right spot), but I haven't been able to reproduce this so it may have just been due to something I was doing at the time messing with things. Also of note, if the frame is floating its position is not restored, but this is also the case for macro frames in 1.7.

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This change is 

[Phergus]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Irarara)