Changes listed below.
- add `operator=` method to the `module::Socket` class to simplify the binding
- add an automated `create_reset_task` method in the `module::Module` class
- add `get_n_input_sockets` and `get_n_output_sockets` methods in `module::Task`
- add `tools::Interface_is_done` to `tools::Sequence`: enable auto-stop in
  `tools::Pipeline`
- add `exec_step` method to `tools::Sequence`: enable task by task execution
- improve `tools::Sequence`: new task is added to graph if all input sockets are
  fed
- implement `get_info_bits_pos` method in `module::Extractor_RSC` class
- improve `module::Switcher`: enable different type and number of elements in
  `commute` and `select` tasks
- plug CWD socket to the RS decoder (to know if the decoder found a codeword)
- replace reference members by copy in modules (to simplify the binding with
  `py_aff3ct`)
- add documentation of some tasks
- fix doc requirements
- fix the LDPC BP flooding/layered decoder (inter-frame SIMD)
- fix the `puncture` method prototype of the `module::Puncturer` class
- fix AZCW simulations
- unbind adaptors when a `tools::Pipeline` is destroyed (avoid bugs)
- disable backtrace on Android NDK.