mq: fix qrefresh case sensitivity (issue3271) When calling qrefresh with filenames, the filenames were being treated as case-sensistive on case-insensitive file systems. So 'qrefresh foo' would not match file 'Foo', and it failed silently. This fix makes it work correctly on case-insensitive file systems. Previously the matching function was applied directly to the filenames. Now we apply the matching function through repo.status, which handles the case logic for us. A side effect of using repo.status is that if the qrefresh file doesn't exist, there is output stating it doesn't exist. Adds a test to an existing mq refresh case test.