Edit partially working

The compatibility layer is coming on nicely, to the extent that the !Edit application binary from ROOL will run, load a file and allow its editing (but not saving).

Before I go any further on that, I intend to start dropping all use of the original window api (in furniture.h) in favour of the newer and much more flexible composite_window interface.

I'd spent a lot of time trying to think of a good way to describe complex windows with multiple panes, toolbars, combined status and scroll bars, etc. In the end, I decided to avoid any descriptive mechanism in favour of providing a toolbox of useful widgets to be combined programmatically. The idea is that, as long as they are flexible enough, a descriptive system (textual, or data structure based) can be added later by simply writing an interpreter layer.

I'm not likely to get very much done in the next month (just like most months, unfortunately), but that's where I plan to focus when I get a chance. Once the compatibility library starts using that mechanism, I can go back to implementing more RO system calls until I can get some proper applications running.

I'll try to add a screenshot in the next day or so.