langs: Add IsDefault field to Language struct

[jmooring]

While ranging through .Page.AllTranslations or .Page.Translations, it would be useful to know if the current language is the defaultContentLanguage. Those methods return the page collection sorted by language weight; the first may or may not be the default.

This would be a convenience method so that you could do this:

{{ range .AllTranslations }}
  {{ if .Language.IsDefault }}
     ...
  {{ end }}
{{ end }}

instead of this:

{{ range .AllTranslations }}
  {{ if eq .Site .Sites.Default }}
     ...
  {{ end }}
{{ end }}

The first is, at least to me, easier to understand

If we do something like this, the API may depend on pending dimensions work.

[bep]

If we do something like this, the API may depend on pending dimensions work.

Yes.

[jmooring]

This has already been implemented:
fc0da8b#diff-c7cf0d263e118b30aba8670e149a434527d8913c7c1d9ce26fc1934044428651R53

Can we export the field?

[bep]

See c011f6c