interp: Refactor format help and also include options
interp: Add -o name=@path to load file content as value (not documented yet, might change)
interp,decode: Expose decode out value as _out (might change)
interp: Refactor foramts.jq into format_{decode,func,include}.jq
interp: Refactor torepr into _format_func for generic format function overloading
interp: Refactor -o options parsing to be more generic and collect unknowns options to be used as format options
decode of decode alises
func for format overloaded functions
include for format specific jq functions (also _help, torepr etc)
flac_frame: Add bits_per_sample option
mp3: Add max_unique_header_config and max_sync_seek options
mp4: Add decode_samples and allow_truncate options
avc_au: Has length_size option
hevc_au: Has length_size option
aac_frame: Has object_typee option
doc: Rewrite format doc generation, less hack more jq
Now repl, slurp and help implemented using same query rewrite.
Include filename context in error if possible.
Add spew function that does opposite of slurp.
Start of help infra, not done or documented yet.
Show error pointer on parse error.
Rename internal eval to _eval and make eval be wrapper that
does rewrite and has various eror handling etc.
Nicer repl, slupr and help errors.
