libdatrwxx [WP][API]: make use of new multi-line feature
Multiline messages can be passed to the reporting functions and exceptions. Asserting and warning macros are adjusted accordingly. The locations where they are used are similarly adjusted. We no longer distinguish between reports which output only a single-line message (argument M to macros) and such reports, which use output operators to report additional values (argument V to macros). The string passed by M now may contain newline characters as well as argument M may contain an expression which makes use of stream output operators to print values of variables.