Suggestion: Support multiline strings without backslash escapes

[thomashoneyman]

Is your enhancement request related to a problem? Please describe.

I find it a little noisy to parse multi-line documentation strings where line breaks use backslash escapes, as seen here:

@doc 
  "My documentation string that \
  \spans multiple lines \
  \before ending"

Describe the solution you'd like

I'd like to see multi-line string support as seen, for example, in PureScript, where a triple-quote string prevents special parsing of escaped symbols. The above could be written as:

@doc
  """
  My documentation string that
  spans multiple lines
  before ending.
  """

This form is also seen in, say, Python's support for multi-line docstrings (Python allows this form in general, not just in docstrings).

[jwiegley]

I enjoy having the option of multiline strings also.