Point to a version of ti92pluspc with correct unicode support

I have a github repo (https://github.com/sterpe/ti92plus) which hosts a version of of ti92pluspc.ttf where I used fontforge to fix the unicode support in the original file hosted at http://ufont (and others).  

I think maybe the generally available file was never completed so a bunch of the unicode mappings were mixed up...anyway, the link I am patching in fixes that.

Thanks.