[commit: ghc] wip/travis's head updated: Add user documentation for explicitly-bidirectional pattern synonyms (535b37c)

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Repository : ssh://git@git.haskell.org/ghc

Branch 'wip/travis' now includes:

     12644c3 New parser for pattern synonym declarations:
     40e7774 Add parser support for explicitly bidirectional pattern synonyms
     0279a7d Typechecker support for explicitly-bidirectional pattern synonyms
     d84a5cc Add renamer support for explicitly-bidirectional pattern synonyms
     25c2eeb tcLookupPatSyn: look up the PatSyn record for a given Id
     6a78503 Typecheck the wrapper definition of a pattern synonym, after everything in the same scope is typechecked
     32bf8a5 When computing minimal recursive sets of bindings, don't include references in wrapper definitions for explicitly-bidirectional pattern synonyms
     f3262fe Add test cases for explicitly-bidirectional pattern synonym
     893a261 Refactor PatSynBind so that we can pass around PSBs instead of several arguments
     3219ed9 Add note about renaming of pattern synonym wrappers
     535b37c Add user documentation for explicitly-bidirectional pattern synonyms