Adding info to constants

[Suzanna-Linn]

This PR replaces draft #167.

After commenting in #160, I'm adding these fields to the constants that have associated values:

• in constants with one associated value:
  • value-type: same as Rulesets for table-based function params #143.
  • range: array [ start, end ].
  • default: default value.
  • enum: category of constants, or group of categories.
  • details: anything else in the Wiki table.
  • access:
    • "arg": the value is always an argument.
    • "read": it's only used when reading.
    • "write": it's only used when writing.
    • "read/write": default, not used in the file.
  • values: an array when there is more than one associated value (or only one, but with an informative name):
    • name
    • value-type
    • range
    • default
    • enum
    • details
    • access

JSON file with the added fields: https://suzanna-linn.github.io/slua/wiki-constants-values.html

LSL definitions browser with the updated YAML file: https://suzanna-linn.github.io/slua/reference-lsl-definitions