Simplify and allow for sharing of "delayed style" parsing

[patritzenfeld]

• Parsing now produces LangM' m Submission value
• The encapsulated value is shared and fed to the check functions
• aborts with reject feedback on parse errors
• Added useParserAnd function to allow for further processing, i.e. with Delayed

[jvoigtlaender]

Oben steht, dieser PR würde #72 schließen. Ich denke jedoch eher, dass er #74 schließen würde. Siehe auch #74 (comment).

[jvoigtlaender]

I think the useParserWithFallback/parseWithFallBack function should, upon failure, at least optionally display the string it was trying to parse. Because that can be a string deeply nested in the original structure obtained from the HTML form. When, for example, the complainAboutMissingParenthesesIfNotFailingOn hits, then it would be good to display to the user which string it was that had this problem. (In the truth table filling case, it could be any of the column headers or answer formulas. The field number is not available anymore when parseWithFallBack runs. But displaying the offending string should help the student understand where something bad happened. In the Delayed parsing functions in logic-tasks this is not relevant. There, the complaining always concerns the whole input field, because there is only one big input field instead of many small strings each of which is looked at separately.)

[jvoigtlaender]

There should probably also be a version of the "parser for second phase after input field structuring" without the fallback behavior. That is, something of type

  (Monad m, OutputCapable (ReportT o m))
  => Parser a
  -> (ParseError -> State (Map Language String) ())
  -> String
  -> LangM' (ReportT o m) a

(potentially plus the argument for optional turning-on-the-string-showing)

It's the function one gets from the other function by providing pure () as the fallback parser and ignoring the first argument of the messaging function.

[jvoigtlaender]

Maybe the "optional-string-showing" should simply be realized by prefixing (String -> ... to the -> ... -> State (Map Language String) ()) functions?