Update Alan LangDef: v2.0.0 (!78) · Merge requests · André Simon / highlight

This commit fixes some keywords issues and improves the syntax:

kwd-ID 1: Add missing Keywords: indirectly, meta, transitively.
kwd-ID 2: Add missing Prefefined Classes: literal, string.
Add new keywords group (ID 3) and move hero into it (from kwd-ID 2). For more details on these changes, see discussion with Alan develepor Thomas Nilefalk (@thoni56) at: https://github.com/alan-if/alan-docs/issues/15 https://github.com/alan-if/alan-docs/issues/17

Update Alan LangDef: v2.0.0