Improve navigation.yaml to reduce repetition (especially for language-specific text)

[NSoiffer]

There are a lot of navigation rules that are independent of speech. Many more can be made independent and also avoid repetition. E.g., there are 6 rules that have

      - test:
        - if: "$NavCommand = 'MoveNext'"
          then: [{t: "move"}]
        - else_if: "$NavCommand = 'ReadNext'"
          then: [{t: "read"}]
          else: [{t: "describe"}]

A new (language-specific) rule can be created and then these could defer to it by setting some env variable to trigger what to say/act as params. The rules containing the above can then be language independent. The language rules would -include the base navigation rules.

Other than learning the trick to do this, this is a good first project rule.

[NSoiffer]

An alternative idea is to add start node in navigate.rs before the call. In navigate.yaml, match on that node and define a bunch of variables such as

• Left: "left"
• Right: "right"
• SayMove: "Next/Previous" # Write a rule to test this and it does the above block to say "move", "read", or "describe"
• IsNext: "$NavCommand = 'MoveNext' or "$NavCommand = 'ReadNext' or "$NavCommand = 'DescribeNext'"
• IsPrevious: ...

One can reference these variable to isolate language issues.

$IsNext can save some repetition. Also, combining Next/Previous to a single command would help them stay in sync.