Apply clang-tidy modernize-use-using to all tests (#199)

Run clang-tidy 7.0 with `-checks='-*,modernize-use-using' -fix`
against TU-s of all tests.

Manually refactor numerous typedef-s
- where missed by modernize-use-using check, not uncommon
- in code snippets in comments

Outcome is that searching for lower-case whole word typedef
in sources of all the tests should return no matches.

io/test/bmp_write_test.cpp

@@ -20,7 +20,7 @@
 using namespace std;
 using namespace boost::gil;
 
-typedef bmp_tag tag_t;
+using tag_t = bmp_tag;
 
 BOOST_AUTO_TEST_SUITE( gil_io_bmp_tests )