Replace USE_PYTHON* by USES=python.

This commit consists of area51's r10314 and r10356 patchsets.

Approved by:	rakuco (mentor)
Allow installing contrib modules in a different prefix than /usr/local

PR:		194160
Submitted by:	jhujhiti@adjectivism.org
mail/rainloop: Rework to avoid unnecessary overriding do-extracts target

There's no reason to roll-your-own extraction target, the stock target
works fine.  Remove and and adjust do-install accordingly; there's not
change the pkg-plist.

While here, remove RVER derivative of PORTVERSION.  This looked wrong to
me -- I doubt the RVER will end in ".164" after the PORTVERSION is
incremented.  If anything, the PORTVERSION would be derivative of RVER,
but for now I just have two seprately defined variables.  Also, unmask
installation commands.
- Add USES=libtool and INSTALL_TARGET=install-strip
- Remove pthread patching
Add USES=libtool and INSTALL_TARGET=install-strip
- Add USES=libtool and INSTALL_TARGET=install-strip
- Remove pthread patching
math/taucs: Removing unnecessary do-extracts target; use NO_WRKSUBDIR

With NO_WRKSUBDIR set, there's no need for a roll-your-own extraction
target, so remove it from this port.

While here:
  - use <options> instead of <pre> + <post> includes
  - Wrap the compound commands in parentheses and use "&&" conjunctions
    instead of ";" for better multijob support
  - Remove several command masks (@) that were suppressing log output
  - Remove duplicate (and broken) softlink creation in lib target
  - Fix second (also broken) softlink creation in do-install target
  - Revbump for last
  - Fix WWW whitespace
  - Remove redundant @dirrm
Remove redundant patches mistakenly added back in r367909.

Pointed out by:	tijl
Add USES=libtool and INSTALL_TARGET=install-strip
Convert to USES=charsetfix and USES=libtool
New port: security/py-rekall

The Rekall Framework is a completely open collection of tools, implemented in
Python under the GNU General Public License, for the extraction of digital
artifacts from volatile memory (RAM) samples. The extraction techniques are
performed completely independent of the system being investigated but offer
visibility into the runtime state of the system. The framework is intended to
introduce people to the techniques and complexities associated with extracting
digital artifacts from volatile memory samples and provide a platform for
further work into this exciting area of research.

WWW: http://www.rekall-forensic.com/