make provision for readRawLine to ONLY return the unread portion of the current line (w/o reading the next), to allow the Gullet to combine with peek'd tokens
fixup readRawLine to combine peeked tokens with the unread portion of the current line from the Mouth
add a data attribute to floats and listingblock to hold the raw listings data (or other data)
Added a css resource for the listings package
Added templates to provide link to listing (or other float) data attribute
fixed bug not counting the column used by ids (and sometimes yielding apparently empty lines); copy the raw listing data onto a data attribute of listing elements; add resource to ltx-listings.css
added an extra testcase of no options provided to lstlisting; updated tests to include the data attribute