This introduces three new things:
* `handleException` which prints out exception details and its stack
trace.
* `handleExceptionWithAsyncTrace` which does the same, but also prints
the async trace if any.
* `LIX_BLOCK_ON` which is awaits a promise and adds an exception trace
if an exception got thrown, similar to `LIX_TRY_AWAIT`. However, this
is not supposed to be used in async functions, but on callsites of
`aio.blockOn()` which is especially useful for Hydra[1].
For `LIX_BLOCK_ON` I had to introduce another function because there's
apparently no way to implement all of it in a macro: on macros with
compound statements the return value must be a trivial expression at the
bottom, i.e. no `try`/`catch`. Now, returning the value from the
`try`-block requires the variable to be defined up-front, but for that
we'd need to know the type-name. Hence the construction with a
template-function being invoked by a macro that injects the current
source-location.
[1] https://git.lix.systems/lix-project/hydra/pulls/52
Change-Id: I56cc92c94f7e8f0be5d4dc5a7d8cb21a92e776ef
Maximilian Bosch
e23bed5e64