Avoid acquiring dada buffers when the buffer is full (writer) or when it is...
This merge avoids blocking Dada clients. Whenever a client tries to acquire a new data block, the client checks if the block is acquirable. If the block is not acquireable, the client sleeps instead of blocking until the acquisition succeeds.
This behavior allows to interrupt the client by calling the method client.stop_next(). Addtionally, client.disconnect() and client.connect() methods are more robust against different buffer states.