Text.Lexer: fix behavior of `surround`
Text.Lexer: fix behavior of `surround`

`manyTill` is a `Recognise False`. It will recognise either nothing,
or any number of `l` followed by an `end`. This makes it unsuited for
`surround`, because the end character is required.

kojiromike/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev,uuhan/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev,uuhan/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev,uuhan/Idris-dev,kojiromike/Idris-dev