This patch fixes the section of the rubber info page (teTeX -> TeX).
The section teTeX does not exist any more (#424946).
Use basename rather than pathname
Use OS-specific PATH separator
Support both XDV and PDF output formats for XeTeX
Rename XeLaTeX module to XeTeX

XeTeX and XeLaTeX are equivalent (xelatex is normally just a link
to xetex), so it makes sense to provide xetex rather than xelatex
module as the former is more generic.
Enable support for LuaTeX