Tiled 1.2.2 released

This patch release brings an assortment of small fixes and improvements. Maybe most importantly, it enables backwards compatibility of the JSON export option with older versions of Tiled. Those who need this can enable the new “json1” plugin (and optionally disable the standard “json” plugin, to avoid ambiguity).

This is a companion discussion topic for the original entry at https://www.mapeditor.org/2019/01/29/tiled-1-2-2-released.html