This was started in c5ae047e but did not include generation of parse.auto.c.
The parser has also been improved with better errors and multiple passes to reduce dependency on ordering and produce and cleaner output.
Option order resolution now includes cycle detection.
Parse enough of config.yaml to auto-generate config.auto.h and config.auto.c.
This commit implements most of the infrastructure needed to migrate the rest of the build code to C, but each set of auto-generated files will present its own challenges.
The build is now dependent on libyaml. At this point there is no need for a hard requirement, but that will come soon so it seems better to add the dependency now.
Since the pack type was stored in 4 bits, only 15 values were allowed (0 was reserved).
Allow virtually unlimited types by storing type info in a base-128 encoded integer following the tag when the type bits in the tag are set to 0xF.
Also separate the type IDs used in the pack (PackTypeMap) from those presented to the user (PackType). The prior PackType enum exposed implementation details to the user, e.g. pckTypeUnknown.
The help data can be represented more compactly in a pack and this separates data needed for help from data needed for parsing, freeing each to have a more appropriate representation.
