Make the codebase consistent, we already have a lot of implicit pointer comparisons.
Exception: Stay explicit on return's, example:
return _db != nullptr;
Signed-off-by: Michael Schuster <michael@schuster.ms>
We keep NULL in the pure C files in src/csync/std and test/csync.
We also replace Doxygen documentation referring to "NULL" to
"\c nullptr" (formatted as code).
Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
