caller access to exception flags

[stevengj]

Right now, I'm clearing the exception flags after calling a function and possibly checking them. It might be nice to allow more flexible handling of them. e.g. leave them uncleared and let the caller check them if she wants to.

Ideally, I would imitate what Julia does with fp exception flags for binary fp, but there doesn't seem to be much there right now. cc @andreasnoack

[ScottPJones]

I believe that the library can be compiled where the exception flags are passed on every call, instead of being global state (which is a problem for multithreaded access to the library).
Might that be a cleaner path for the future?