Allow the user to specify their own delimiters

- Remove DELIM constant
- Add brewFindDelim internal function, which takes the current line
  being processed and the list of delimiters. It returns a list of which
  delimiters were found.
- Add the following parameters to the brew function: delim.code,
  delim.comment, delim.catcode, and delim.template
Move custom delimiter arguments to the 'brew.delim' option