Made hex escaping of char codes in strings always print alphabetic hex digits in upper case (fixes test failures on Allegro).
Made hex escaping of char codes in strings always print alphabetic hex digits in upper case (fixes test failures on Allegro).

vsedach/Parenscript,VincentToups/parenscript,JDReutt/parenscript,fredericksilva/Parenscript,3b/parenscript,manuel/parenscript