[Kinflou]

Step 2 of the compatibility work (core#119, ComlineProject/runtime#15), documenting ComlineProject/core#159.

• Versioning reference: a new Compatibility facts section covering the package id, each protocol's line, each function's since, the shape hash and the encoding parameter hash. It gives the line rule (what reaches a protocol, dependencies by reach, package wire changes moving every line, renames not counting) and explains that lines and sinces name releases only (0.x minor before 1.0, dev builds carry what they lead to, a raised or 1.0 release renames them). It also says what goes into the shape hash and how the facts are stored. The manifest-changes table gains id (changed: major).
• Packages guide: the config.idp table gains id, and the example shows it.
• comline inspect: shows the latest build's line, shape hash and sinces for the package's own protocols, plus facts in --json. The "Not shown" note is updated.

zensical build --strict passes locally.