Clear all tests out at the beginning.

* sly-tests.el (sly-tests--undefine-all): New function.

(cherry-picked from SLIME commit 247f579)

Conflicts:
	ChangeLog
* Makefile (compile-swank, run-swank): New targets.

(clean-fasls): Also remove ~/.sly/fasl/.

(cherry picked from SLIME commit
1426f9e35606aad88758c0e74c462e00dd240882)

Conflicts:
	Makefile
Fix swank-sbcl.lisp.

(cherry picked from SLIME commit
3ac4c5b6afb83186da528dc0424f0016eafc5472)

Conflicts:
	lib/lisp/backend/swank-sbcl.lisp