compile-fast-path: Update for new syn

patch 16bc32a: Put nom::Context::List behind feature gate

portus 0.5.2

CongAlg: split trait to support dynamic dispatch

Because it contains an associated type, it was previously impossible to
express dynamic dispatch across congestion control algorithms; i.e., in
the case where the runtime allows dynamic switching between a battery of
congestion control algorithms.

Therefore, remove the `Config` associated type. Instead, implementations
of `CongAlg` will contain configuration options. Rename the `create()`
method to `new_flow()` and have it take `&self`, and produce a value of the
associated type `Flow`, which implements the trait `Flow`. Then move
`on_report()` and `close()` functions from `CongAlg` to the trait
`Flow`.

Finally, to support dynamic dispatch, add non-public trait `CongAlgDyn`,
which for all `T, C: CongAlg<Flow=T>` will `Box` up the return value of
`new_flow()`.

Temporarily remove python bindings for generic-cong-avoid; will mimgrate
these to the generic-cong-avoid repo.

Stable release for tutorial.

portus api: deduplicate programs across flows

This commit modifies the CCP API to expect users to install all programs
in the new init_programs function, when portus starts running. To make a
flow use a particular program, there is a new set_program function; when
installing, users also specify a name for each program. In the datapath,
now, programs need not be duplicated across flows. This also bumps the
libccp submodule version to match the corresponding changes in libccp.

lang: Make default Scope useful