Point to string affected by locale

[ErnestoNCarrea]

I noticed that the function toStringPoint() in AbstractGeometry.php is affected by locale configuration and can sometimes emit coordinates with comma as a decimal separator (which will fail when persisting to a MariaDB database).
I think the problem is -at least- in line 227, in "vsprintf('%s %s', $point)" where $point is an array of two float values, and vsprintf will respect locale when implicitly converting to string.

[kapiwko]

Unfortuanelly in general that library is not usable when locale has comma as decimal point - I always got POINT(1,1).