Unstable changes in main

[Brian Rice]

I have a set of changes I'd been debugging locally for a week, and  
progress has slowed, so I've pushed them into the main repository for  
increased exposure. There is a tag on the main repository  
StablePoint-0.3.5.1 which is before all of these patches, so stop  
there if you don't want to deal with this. I'll reply when the issues  
are resolved.

The changes are:
1) A big change and cleanup in how directories are handled, including  
trying to make LogicalDirectory a general facility, basically where  
they hold onto a block used to update their locators when needed (for  
Directory Home, this is on starting the image; for Directory Current,  
this is just on chdir calls). This may turn out to be a poor design  
decision, but I needed to make progress. The intent is that a  
SlateDir can be made and recorded during the post-bootstrap phase,  
which the image then remembers when it looks for standard sources  
(even if we have to change "load: 'src/...'" into "load: 'src/...'  
&from: SlateDir" or "load: SlateDir / 'src/...'). This would allow  
Slate to run from anywhere in the file system without complaint.

2) Fixes to Directory Proxy to make it Dictionary-based instead of  
slot-based, since the latter mixes up the object-oriented knowledge  
with other information, and was causing some real headaches. It also  
mostly works now. ;)

3) A refactored UI for Restart objects, mostly so that only the  
Debugger needs to know which console it's using, and so that the  
debugger mediates the UI requests of the Restart objects. This seems  
to be the patch that is causing most of the bootstrap issues, since  
it's become hard to debug new images if the restart ui is slightly off.

The fixes are probably easy, but I haven't perceived them yet. I'll  
tag the repository again when it's resolved.

--
-Brian