Increase resolution of camera output

I don't like doing this directly in the sources, but I am anyway. Optimally,
there should be a way of passing this to the library and having it create a
capture of the specified dimensions. Perhaps I'll implement that in the future.
Allow user to set size of capture.

The original function now exists and works by delegating its work to a function
that requires more arguments. This function is exposed in the header, making it
callable if the user desires a larger picture.