Docstring edits.  waitFrameCapture returns the errorCode.

I added a to the docstring of each function.  I set waitFrameCapture to return the errorCode instead of passing it to VimbaException.  For a hardware trigger this lets the user handle errorCode -12 where a timeout has been reached.  Not handling this error causes problems with the camera I think after either frame.getBufferByteData or camera.revokeAllFrames.