For correct representation of operator symbols used in the sessions
List-Infinite, Nat-Interval-Logic, AutoFocus-Stream in generated HTML theory
documentation.


Modifications of src/Pure/Thy/html.ML (the Pure and HOL logics must be rebuild
afterwards):

  - Additions:
    ("\\<up>", (1, "<span class=\"largersymbolstyle\">&#x2191;</span>")),
    ("\\<down>", (1, "<span class=\"largersymbolstyle\">&#x2193;</span>")),
    ("\\<updown>", (1, "<span class=\"largersymbolstyle\">&#x2195;</span>")),
    ("\\<Up>", (1, "<span class=\"largersymbolstyle\">&#x21D1;</span>")),
    ("\\<Down>", (1, "<span class=\"largersymbolstyle\">&#x21D3;</span>")),
    ("\\<Updown>", (1, "<span class=\"largersymbolstyle\">&#x21D5;</span>")),
    ("\\<NoMsg>", (1, "&#x03B5;")),
    ("\\<Msg>", (3, "Msg")),

Addition to lib/html/isabelle.css for correct represenation of some arrow
operators in generated HTML theory documentation (above operator symbols of the
form <span class=\"largersymbolstyle\">SYMBOL</span>): Add following line at
the end of the file:

  .largersymbolstyle, largersymbolstyle {font-size: 150%}
