Moved reduction-emitting functions into a new Reductions module to make them easier to maintain; next we'll refactor them into several smaller functions.
Fixed the .gitignore exclusion patterns for generated lexer and parser source files so they work properly again.
Moved the recently-refactored ParserTypes, ParserTables, and Reductions modules out of the FsYacc module into the containing namespace.
Moved the FsYacc constants out of the FsYacc module into a new FsYaccConstants module.
Removed unnecessary 'open' declarations.
Refactored the reduction action-emitting functions to simplify them; also modified the reductions-emitting code to use TaggedGrammar instead of ProcessedSpecification to help ensure consistency (e.g., of production rule indices).
Removed the obsolete TaggedGrammar.toGrammar function.