Finish operator table.
Install fixities in parse state as we find them.
Starting the parser knot.
ErmineParserT, to tie the type-level knot.
Derive MonadIO in ErmineParserT; probable initial ParserState.
Decompose the map from the loader in MapCache.
Replace liftState with `zoom` from lens.

Thanks to @shachaf for the suggestion.
Definitions for two-phase module parsing.
Push holes in Module parser down to 'importedFixities'.
Remove ErmineParserT.
wholeModule needs the dependency Module values.
More wholeModule docs.
Move ModuleHead to Syntax.Module and make it a real type.
Design for sorting ModuleHeads & dependencies in preparation for Module parsing.
Implement the graph fetch for ModuleHeads.
fetchGraphM works just fine for empty starting points.
Some of topSort
Test a fetchGraphM property.
Another fetchGraphM property.
Module header for E.S.Module.