Reading input files

[wpbonelli]

Need the capability to read MF6 ASCII input files. May eventually move to devtools, not sure.

[wpbonelli]

Sketched a plan here MODFLOW-ORG/modflow-devtools#193 (comment)

[wpbonelli]

on the rationale for LR(1) conforming grammars and avoiding ambiguity

• https://tratt.net/laurie/blog/2020/which_parsing_approach.html
• https://lark-parser.readthedocs.io/en/stable/parsers.html#lalr-1