Specify syntax of whitespace around operators

This is likely to be the most challenging task of updating the Haskell 2010 language report. We have to somehow incorporate the rules decided upon in https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0229-whitespace-bang-patterns.rst into the report, while at the same time not diverging too far from the BNF-like formalism that the report currently uses.

Start by reading the current Haskell 2010 language report's whitespace and operator grammar, then compare it with ghc-proposals proposal 0229-whitespace-bang-patterns.rst. Done means the report incorporates the decided whitespace rules without diverging unnecessarily from its existing BNF-like formalism.

Written by the indexing model from the issue text.