Update README.md

Added link to Stack Overflow

loop next/prev sheets on hotkeys Alt+PageUp/Alt+PageDown

var FOCUS_OBJECT_THUMBNAILS = 0;
var FOCUS_OBJECT_MAIN       = 1;
var FOCUS_OBJECT_NOTES      = 2;

bug with select slide on open

asc_setCanBranding -> setCanBranding

add method asc_getLicenseType

send cell horizontal align general ('none')