Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Import of liblzma, xz, xzdec, lzmainfo from vendor branch
Add support for xz and lzma to lesspipe.sh (xzless, lzless)
Bump __FreeBSD_version

Approved by: delphij (mentor)
MFC after: 2 weeks

Fix handling of filenames containing whitespace.

PR: bin/112860
MFC in: 3 days

In rev. 1.2 we have introduced a fallback handler for files with unknown
extensions. This seems to be unnecessary and prevents less(1) from being
able to detect file changes, so remove the part.

Submitted by: Eric Huss <e-huss netmeridian com>
PR: bin/102624
Discussed with: des
MFC After: 3 days

Handle presumably uncompressed files with cat; exec the handlers.

MFC after: 1 week

Add an embellished lesspipe.sh as described in the man page.
P.S. it is stupid I have to define both SCRIPTS and SCRIPTSNAME.