Support highlight-escape-sequences

Hi,

would it be possible to add support for highlight-escape-sequences?

These are the faces it defines:

(defface hes-escape-backslash-face
  '((default :inherit font-lock-regexp-grouping-backslash))
  "Face to highlight an escape backslash.")

(defface hes-escape-sequence-face
  '((default :inherit font-lock-regexp-grouping-construct))
  "Face to highlight an escape sequence.")

They are inherit from pre-defined ones, so probably you don't need to do anything actually. It's up to you. :)