Re-structure sat-rs

- Add new shared subcrate satrs-shared to split off some shared
  components not expected to change very often.
- Renmame `satrs-core` to `satrs`. It is expected that sat-rs will remain
  the primary crate, so the core information is superfluous, and core also
  implies stability, which will not be the case for some time.

satrs/src/lib.rs

@@ -0,0 +1,50 @@
+//! # sat-rs: A framework to build on-board software for remote systems
+//!
+//! You can find more information about the sat-rs framework on the
+//! [homepage](https://egit.irs.uni-stuttgart.de/rust/sat-rs).
+//!
+//! ## Overview
+//!
+//! The core modules of this crate include
+//!
+//!  - The [event manager][event_man] module which provides a publish and
+//!    and subscribe to route events.
+//!  - The [pus] module which provides special support for projects using
+//!    the [ECSS PUS C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
+#![no_std]
+#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#[cfg(feature = "alloc")]
+extern crate alloc;
+#[cfg(feature = "alloc")]
+extern crate downcast_rs;
+#[cfg(any(feature = "std", test))]
+extern crate std;
+
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+pub mod cfdp;
+pub mod encoding;
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+pub mod event_man;
+pub mod events;
+#[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+pub mod executable;
+pub mod hal;
+pub mod hk;
+pub mod mode;
+pub mod objects;
+pub mod params;
+pub mod pool;
+pub mod power;
+pub mod pus;
+pub mod request;
+pub mod res_code;
+pub mod seq_count;
+pub mod tmtc;
+
+pub use spacepackets;
+
+// Generic channel ID type.
+pub type ChannelId = u32;