In Radiant main() method, add putenv("LC_NUMERIC=C").

In Radiant main() method, add putenv("LC_NUMERIC=C").
sscanf() and *printf() calls are all over the code, which are
locale-sensitive.  gtk_init() sets all locales.  So if you're in
Germany, your printf()'s will output e.g. "10,5" for ten and
a half.  Reading floating points with sscanf() is also totally broken
in locales such as Germany.  So, we can't really get rid of all the
*scanf()'s and the *printf()'s.  Instead, set LC_NUMERIC to "C".

git-svn-id: svn://svn.icculus.org/gtkradiant/GtkRadiant/trunk@334 8a3a26a2-13c4-0310-b231-cf6edde360e5