blight.rkt: move all top-level calls and definitions to blight-run function and install exception handlers.
add basic top-level exception handling with dialogue
error handling: fix error reporting. now calling default handler correctly
error handling: pass some context to exception handling dialog to allow for closing blight and (potentially) restarting it.
Remove blight-run
blight.rkt tidy code
error handling: remove thread from ctx
Merge branch '4DA-master'