[lucida] need to manually specify bold/italic fonts with current fontspec

[Karl Berry]

     From current fontspec documentation:
    "Fonts selected by filename must include bold and italic variants 
    explicitly."

I'll ask Will to change that. It is true in a sense, but misleading.
If you look on the next page of fontspec.pdf, it talks about .fontspec
files, which we invented precisely to avoid the need to explicitly
specify everything when finding fonts by filename.

Thus we provide lucidabrightot.fontspec et al. in the Lucida
distribution; \setmainfont{LucidaBrightOT.otf} definitely worked in the
past. It was intended to work reliably going forward, however, I now get
myriad "font not found" messages. It is too frustrating. I'll write Will
about that too. Sigh. -k