Assertion with an optional message

[CsatiZoltan]

Feature request

Is your feature request related to a problem? Please describe.
I would like to test for preconditions and postconditions, but only when compiled in debug mode. Printing a message why something fails is useful. On the other hand, T8_ASSERT, similarly to the built-in assert, only accepts an expression, no optional message.

Describe the solution or feature you'd like
A convenience macro, e.g. T8_ASSERTF would be nice.

Describe alternatives you've considered
To achieve the same effect, we now need to use the more verbose

#if T8_ENABLE_DEBUG
   if (!condition)
      SC_ABORTF("Error message");
#endif

Alternatively, Boost has BOOST_ASSERT_MSG. There are other tricks, such as

assert(("Error message", condition));

See StackOverflow for more details.

Estimated priority

"Priority: low" Should be solved eventually

Additional context
This feature request concerns assertions, not logging. For that, functions such as t8_global_productionf already exist.