Fixed error-behavior-restart-case in src/macros.lisp

* src/macros.lisp (error-behavior-restart-case): fixed handling of
  warning-condition parameter; an error is signaled if 'warn or #'warn
  policy is requested when no warning-condition is specified
* test/macros.lisp (test error-behavior-restart-case-root::smoke):
  test this new behavior
Renamed mock error conditions in test/conditions.lisp

* test/conditions.lisp (mock-error/reference-condition): renamed
  foo-error -> mock-error/reference-condition to avoid name clash