Do not resolve escapes in some cases

[Vladimir Markelov]

Now \n and \t are always substituted with their real values. But for shell execution and cd command it is not good: on Windows it conflicts with paths, so a user may have hard time when using directories starting with 't' or 'n'. E.g, cd .\target\debug must be cd .\\target\debug.

Replace escapements only for quoted strings.

[Vladimir Markelov]

That would be confusing - do not fix