removed obsolete theorems;
handle generic XML markup as well (plain <markup> instead of <... class=markup>);
misc tuning/update according to Pure/Generic/markup.ML;
Arith = FOL +
classes arith < term
consts "0" :: "'a::arith" ("0")
"1" :: "'a::arith" ("1")
"+" :: "['a::arith,'a] => 'a" (infixl 60)
end