Deprecate test tools

Here is the list of deprecated test tools used in Boost Test version 1 and their new analogs:

Old tool New analog tool
BOOST_TEST( predicate ) BOOST_CHECK( predicate )
BOOST_CRITICAL_TEST( predicate ) BOOST_REQUIRE( predicate )
BOOST_CRITICAL_ERROR( message ) BOOST_FAIL( message )

The main reasons for making these changes were conciseness and uniformity. Old deprecated names are still accepted but may be excluded in a future releases. Thanks for Ullrich Koethe, who originally proposed new names.