Remove now unused PBD::string_is_affirmative function

The equivalent function is now PBD::string_to<bool>

libs/pbd/convert.cc

@@ -278,26 +278,6 @@ strings_equal_ignore_case (const string& a, const string& b)
 	return false;
 }
 
-bool
-string_is_affirmative (const std::string& str)
-{
-	/* to be used only with XML data - not intended to handle user input */
-
-	if (str.empty ()) {
-		return false;
-	}
-
-	/* the use of g_ascii_strncasecmp() is solely to get around issues with
-	 * charsets posed by trying to use C++ for the same
-	 * comparison. switching a std::string to its lower- or upper-case
-	 * version has several issues, but handled by default
-	 * in the way we desire when doing it in C.
-	 */
-
-	return str == "1" || str == "y" || str == "Y" || (!g_ascii_strncasecmp(str.c_str(), "yes", str.length())) ||
-		(!g_ascii_strncasecmp(str.c_str(), "true", str.length()));
-}
-
 /** A wrapper for dgettext that takes a msgid of the form Context|Text.
  *  If Context|Text is translated, the translation is returned, otherwise
  *  just Text is returned.  Useful for getting translations of words or phrases

libs/pbd/pbd/convert.h

@@ -57,8 +57,6 @@ to_string (T t, std::ios_base & (*f)(std::ios_base&))
 	return oss.str();
 }
 
-LIBPBD_API bool string_is_affirmative (const std::string&);
-
 LIBPBD_API const char* sgettext (const char *, const char *);
 
 } //namespace PBD