dispatch cases where \ has different meaning.

[lorenzwalthert]

Closes #551 by implementing the suggested solution outlined in #551 (comment). Put that into a file and style it with styler, all \ should be preserved, only quotes should be replaced (does not work well with reprex).

'here
is a string
'
'here\nis a string
'
'here\\nis a string'

Note that for mixing the invisible line break and \n in single quotes, we leave it as is (second example).

[lorenzwalthert]

@krlmlr can you, if you don't see a better way than my solution with the case distinction, check if I handle raw objects in a reasonable way? E.g. to get a character vector from raw, I brutally class(raw) <- "character".

[lorenzwalthert]

Closed in favor of the more concicse, elegant and general implementation (can handle mixed case) in #554.