Fixes #561.

Fixes #563.

Default builds of Firefox remove the previous X remote interface, now causing the use of -remote to silently exit and do nothing. https://hg.mozilla.org/mozilla-central/rev/ef22d8cbf4ef

All utilities print their usage message to stderr, cmp(1) and getflags(8) should do the same.

Found in Arch Linux but never reported upstream: https://bugs.archlinux.org/task/55640

In groff, Heirloom Doctools troff, and neatroff, the `\~` escape sequence produces an adjustable (paddable) but unbreakable space. mandoc, which does not perform adjustment or render to typesetters, supports the escape sequence as a synonym for `\ `, the same as `\0`. This extension is of long pedigree: groff has supported it for at least 30 years, Heirloom for 17, mandoc for 13, and neatroff for 6. Do the same as mandoc to prevent mis-rendering of documents using this escape sequence. Heirloom Doctools troff, a descendant of Documenter's Workbench troff, would be a good place to look for a compatible implementation of the adjustable semantics for this sequence.

* font/pelm: add cjk punctuation for hku.9.font * troff: added back HX

Screen was being queried from within a client after it had been free'd.

Allows this function to always return the proper path in situations where the $PLAN9 environment variable is not set, i.e. a rc login shell.

That is, not only when -r was given. This allows using this veriable in mkfiles across the code base.