0.8.4.10

0.8.4.10
	"brown paper bag" bug fix: initialise the thread->state slot
	when it's created, to fix the most obvious threading problem

	Search order for sbcl.core and sbclrc simplified.

	Manual page edits: updates for contrib/, threading, platforms,
	new sbcl.core search order, etc

	Make "debugger invoked" message print thread id
	asdf-install contrib: new UNINSTALL function deletes a
	package's files.

	New installation variable $(BUILD_ROOT) for use by package
	installers that want to install into a fake root directory