'quill build all' now runs tests

'quill build all' needs to fail if there are test failures; but the
tool_test code had no mechanism for returning the test status.  This
package refactors tool_test.tcl into tool_test.tcl and tester.tcl, and
tester.tcl *does* provide it.  tool_test.tcl now uses tester, and
tool_build uses tester to run all tests and check the status.