fixed 'requires' comments, which are needed for printing of drafts;

--- a/lib/texinputs/isabellesym.sty	Thu Jun 17 14:26:43 2004 +0200
+++ b/lib/texinputs/isabellesym.sty	Thu Jun 17 14:27:01 2004 +0200
@@ -237,7 +237,7 @@
 \newcommand{\isasymsupset}{\isamath{\supset}}
 \newcommand{\isasymsubseteq}{\isamath{\subseteq}}
 \newcommand{\isasymsupseteq}{\isamath{\supseteq}}
-\newcommand{\isasymsqsubset}{\isamath{\sqsubset}}
+\newcommand{\isasymsqsubset}{\isamath{\sqsubset}}  %requires amssym
 \newcommand{\isasymsqsupset}{\isamath{\sqsupset}}  %requires amssym
 \newcommand{\isasymsqsubseteq}{\isamath{\sqsubseteq}}
 \newcommand{\isasymsqsupseteq}{\isamath{\sqsupseteq}}
@@ -281,10 +281,10 @@
 \newcommand{\isasymcirc}{\isamath{\circ}}
 \newcommand{\isasymdagger}{\isamath{\dagger}}
 \newcommand{\isasymddagger}{\isamath{\ddagger}}
-\newcommand{\isasymlhd}{\isamath{\lhd}}
-\newcommand{\isasymrhd}{\isamath{\rhd}}
-\newcommand{\isasymunlhd}{\isamath{\unlhd}}
-\newcommand{\isasymunrhd}{\isamath{\unrhd}}
+\newcommand{\isasymlhd}{\isamath{\lhd}}  %requires amssymb
+\newcommand{\isasymrhd}{\isamath{\rhd}}  %requires amssymb
+\newcommand{\isasymunlhd}{\isamath{\unlhd}}  %requires amssymb
+\newcommand{\isasymunrhd}{\isamath{\unrhd}}  %requires amssymb
 \newcommand{\isasymtriangleleft}{\isamath{\triangleleft}}
 \newcommand{\isasymtriangleright}{\isamath{\triangleright}}
 \newcommand{\isasymtriangle}{\isamath{\triangle}}