- Use common circular buffer implementation
- Handle two channels (hardcoded)
- Receive samples asynchronously from RDMA
- Handle timestamps correctly

- Save input and output timestamps separately
- Avoid timestamp mismatch from trx_play
- Loop on reading samples from input device

- Print to stderr an error previously logged to stdout
- Handle errors with init functions

Switch from a libcapulet-specific MR manager to a generic (and better) hashtable implementation
which will be shared with other parts.

Previously, a global Manager was used for all MRs registered.
Now, every program should declare it's own manager before using MR Mgr functions.

- Support Read/Write
- Returns correct values to higher-level interface
- Warning: still untested