Add multiline format function

Created originally on Bitbucket by asplinsolutions (John Asplin)

Was already merged in Bitbucket before import, marked as merged by the import user

Add format_multiline format function for support of new lines. Looks for \n escape sequence in strings

Example template usage (hyperlink/input field): py3o://function="format_multiline(data)"

Example data string: 'a\nmulti\nline\nstring'