[bugfix] Canvasdraw : userdraw now works also on iOS touch devices :
* Replace "MouseEvent.which" by "MouseEvent.button", as "which property is non-standard (see https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/which)
* Replace evt.identifier == 0 by evt.identifier >= 0, as touch identifier is a unique integer, not always 0
* cleanup trailing spaces
+ Replace "Ariel" font by "Arial", as Ariel is not a default browser font
+ "make all" in canvasdraw also copy generated binary, not only script link
+ minor code formatting