floatflt.sty was removed from texlive due to licensing issues.

--- a/doc/HepMC2_user_manual.tex
+++ b/doc/HepMC2_user_manual.tex
@@ -3,7 +3,6 @@
 \usepackage{graphicx}
 \usepackage{graphics}  
 \usepackage{cite}      % bibliographic sitations 
-\usepackage{floatflt}  
 \usepackage{fancybox}  %allows for shadow boxes etc.
 \usepackage{color}     %allows use of colors (RBG only, I think)
 \usepackage{html}      % allows easy inclusion of links which are