Prevent hyphenation of computer inlines, filenames, and URLs.

Prevent hyphenation of computer inlines, filenames, and URLs.
(Closes #1124391; thanks to Ryan Hofschneider for reporting).

By default, even when hyphenation is enabled (globally),
hyphenation is now suppressed for "computer inlines" (currently,
just classname, constant, envar, errorcode, option, replaceable,
userinput, type, varname -- but probably need to add more) and for
filenames, and for URLs from Ulink.

It can be (re)enabled using the man.hyphenate.computer.inlines,
man.hyphenate.filenames, and man.hyphenate.urls params.