[patch] compile error fixes

[Hilaire Fernandes <hilaire@seul.org>]

 >  > I am getting many other errors though. Such as:
 >  > 
 >  > point.cc: In method `void homothetie_point::sauve_disk(_xmlNode *,
 >  > liste_elem &)':
 >  > point.cc:2208: passing `const char *' as argument 3 of
 >  > `xmlNewChild(_xmlNode *, xmlNs *, const xmlChar *, const xmlChar *)'
 >  > changes signedness
 >  > 
 >  > There are many errors of this type in that file.

There should be no more warning or error expect two I'm not
sure how to fix in the math library :

linear_algebra/misc.gel:184: ERREUR: parse error avant ')'
combinatorics/misc.gel:11: ERREUR: parse error avant 'else'

But this should not be a problem to compile.

Hilaire