FIX: use std::list::sort() to avoid iterator be invalid

[Conzxy]

When configuration is in MSVC Debug mode, I call the replxx_history_save(), following code will cause crash with message:
list iterators is incompatible .

void History::erase( entries_t::iterator it_ ) {
	bool invalidated( it_ == _current );
[...]
}

I find the key code as following:

bool History::save( std::string const& filename, bool sync_ ) {
[...]
	entries_t entries;
	locations_t locations;
	if ( ! sync_ ) {
		entries.swap( _entries );
		locations.swap( _locations );
		_entries = entries;
		reset_iters();
	}
	/* scope for ifstream object auto-close */ {
		ifstream histFile( filename );
		if ( histFile ) {
			do_load( histFile );
		}
	}
	sort(); // all list iterators have been invalid
	remove_duplicates(); // _current is no changed
	trim_to_max_size(); // call erase()
	ofstream histFile( filename );
	if ( ! histFile ) {
		return ( false );
	}
[...]
}
[...]
void History::trim_to_max_size( void ) {
	while ( size() > _maxSize ) {
		erase( _entries.begin() );
	}
}

Here, trim_to_max_size call the History::erase(), the _entries.begin() from current list but _current from previous _entries.