[tex-live] fontmapping file for xetex

[Jonathan Kew]

Hi Karl -

I've just added one more resource that goes with xetex to the TL  
repository: the "font mapping" file tex-text. I've put this under  
texmf-dist/fonts/misc/fontmapping, as it's font-related, but doesn't  
really fit any of the existing places. Please ensure that the xetex  
collection in TL includes this package.

(This "font mapping" is unrelated to "map files" in the normal TeX  
sense. It's the character mapping mechanism used to support DEK-style  
ligatures like '---' -> em dash, `` -> open double quote, etc., when  
using standard Unicode fonts that don't have these encoded in lig/ 
kern tables.)

There are two files there, tex-text.map and tex-text.tec. Strictly  
speaking, only the .tec (compiled mapping table) is needed at  
runtime, and the .map (mapping source) could go elsewhere as a source  
file, but these are so small that it doesn't seem worth separating  
them in that way for now.

JK