Fix utils_string_replace_all() to accept a NULL replacement again

Support of NULL as the replacement was lost in the code refactoring
introduced by revision 5730, and it broke a few plugins.

git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@5965 ea778897-0a13-0410-b9d1-a72fbfd435f5

ChangeLog

+2011-09-28  Colomban Wendling  <colomban(at)geany(dot)org>
+
+ * src/utils.c:
+   Fix utils_string_replace_all() to accept a NULL replacement again.
+
+
 2011-09-26  Nick Treleaven  <nick(dot)treleaven(at)btinternet(dot)com>
 
  * src/editor.c:

src/utils.c

@@ -1556,9 +1556,13 @@ gint utils_string_find(GString *haystack, gint start, gint end, const gchar *nee
 gint utils_string_replace(GString *str, gint pos, gint len, const gchar *replace)
 {
 	g_string_erase(str, pos, len);
-	g_string_insert(str, pos, replace);
+	if (replace)
+	{
+		g_string_insert(str, pos, replace);
+		pos += strlen(replace);
+	}
 
-	return pos + strlen(replace);
+	return pos;
 }