Changed indentation of docstrings in {src,test}/*.lisp, more-conditions.asd

* src/types.lisp: changed indentation of documentation strings
* src/variables.lisp: likewise
* src/conditions.lisp: likewise
* src/macros.lisp: likewise
* src/package.lisp: likewise
* test/conditions.lisp: likewise
* test/macros.lisp: likewise
* test/package.lisp: likewise
* more-conditions.asd: likewise
Moved protocol generic functions to new file src/protocol.lisp

* src/protocol.lisp: new file; contains protocol provided by the more
  conditions system
* src/conditions.lisp (cause): removed; moved to src/protocol.lisp
  (root-cause): likewise
  (condition-references): likewise
  (condition-references t): likewise
  (progress-condition-message): likewise
  (progress-condition-message condition): likewise
* more-conditions.asd (system more-conditions): added file
  src/protocol.lisp
Use fiveam instead of lift in test/*.lisp

* test/conditions.lisp (test suite conditions-root): removed; tests
  just live in the more-conditions suite now
  (test maybe-print-cause.print): converted to fiveam
  (test maybe-print-explanation.print): likewise
  (define-condition-suite): likewise
* test/macros.lisp (test suite macros-root): removed; tests just live
  in the more-conditions suite now
  (test with-condition-translation.smoke/no-cause): converted to
  fiveam
  (test with-condition-translation.smoke/cause): likewise
  (def-fixture with-mock-generic-function/foo): new fixture; define
  and undefine generic function `foo'
  (test define-condition-translating-method.smoke/cause): converted to
  fiveam; use `with-mock-generic-function/foo' fixture
  (def-fixture with-mock-generic-function/foo/initargs): new fixture;
  define and undefine generic function `foo/initargs'
  (test define-condition-translating-method.smoke/initargs): converted
  to fiveam; use `with-mock-generic-function/foo/initargs' fixture
  (test error-behavior-restart-case-root.smoke): converted to fiveam
  (test with-trivial-progress-root.smoke): likewise
  (test with-sequence-progress.smoke): likewise
* test/package.lisp (package more-conditions.test): removed used
  package lift; added used packages let-plus and fiveam; removed
  exported symbol root; added exported symbol run-tests
  (def-suite :more-conditions): converted root test suite to fiveam
  (run-tests): new function; run all tests
* more-conditions.asd (system more-conditions-test): removed system
  dependency on lift; added system dependencies on let-plus and fiveam
  (perform test-op eql :more-conditions-test): use `uiop:symbol-call'
  to call `more-conditions.test:run-tests'