dangling pointer in ofXml

[affa0]

Version 0.11.1 introduced an issue in ofXml, that leads to random undefined behaviour.
std::locale returns a temporary char*, this is saved in auto loc, but the next line ( std::setlocale( LC_NUMERIC, "C" );) invalidates this internal char*, so it should not be used anymore from then on.
But in the line 252 it is used again to reset the locale. This leads to random behaviour down the line as the loc pointer is not valid anymore at that point.

248   float ofXml::getFloatValue() const{
249     auto loc = std::setlocale( LC_NUMERIC, NULL );
250     std::setlocale( LC_NUMERIC, "C" );
251     float f = this->xml.text().as_float();
252     std::setlocale( LC_NUMERIC, loc );
253     return f;
254   }

So this should be changed by saving a deep copy to the char*, maybe like this:

float ofXml::getFloatValue() const{
	std::string loc = std::setlocale( LC_NUMERIC, NULL );
	std::setlocale( LC_NUMERIC, "C" );
	float f = this->xml.text().as_float();
	std::setlocale( LC_NUMERIC, loc.c_str() );
	return f;
}

The same change is need in ofXml::Attribute::getFloatValue, ofXml::Attribute::getFloatValue and ofXml::Attribute::getFloatValue as well.

This issue was introduced in 6678 that tried to fix 6111