Tighter bind to SAT solvers

[weaversa]

tmpnam is not ideal for a number of reasons - the most prominent here being the lack of stability in a threaded environment. It would be nice to replace tmpnam with something like this:

https://stackoverflow.com/questions/6171552/popen-simultaneous-read-and-write

Or, just pick one or more top solvers written in C/C++ and integrate them tightly.

[socketpair]

GCC: the use of tmpnam' is dangerous, better use mkstemp'

I suggest https://en.cppreference.com/w/c/io/tmpfile

[weaversa]

We'd be happy to accept a pull request :-)