Previously, calling e.g. love.graphics.getFont() 10,000 times would retain the object 10,000 times (and release it 10,000 times when the Font object was garbage-collected in the Lua state.) Now it will only retain it once and release it once.
luax_pushtype keeps the object in a weak table and checks the table before creating a new userdata, so it re-uses the object's existing wrapper userdata if it can, whenever the object is pushed to Lua.
This fixes some subtle issues with love objects, where using them as keys in tables would not always work as expected (https://love2d.org/forums/viewtopic.php?f=4&t=39398&p=112388#p112415). It also decreases the amount of new Lua objects created, saving the garbage collector some work.
This means you can now use Variants (used by Channels and love.event, for instance) to send tables as long as they only contain keys and values supported by Variant, AND they are not tables themselves.
To do this we needed to take ThreadVariant out of love.thread, and move it to common.
This also changes event names, instead of 1/2-letter abbreviations, full names!
Alex Szpakowski
Bart van Strien
rude
Bill Meltsner