Fix, need to use absolute path, or we might get caught in virtualenv PATH.
More portable mode implementation work

* On Linux, follow with "ldd" to extension modules, so we can pick up
  the libraries they load once loaded. Since the extension modules are
  loaded on the fly, this is necessary step.

* Fixup the parsing of "ldd" to work fine on Python3 as well. It was
  temporarily regressed.

* Added support for "standalone" as option alias for "portable" mode,
  this is going to become the main name of this feature.

* Added support for comparing to CPython with "standalone" mode being
  used.

* Added test to cover portable mode on Linux.
Added tests for standalone mode.

* Currently passes on Linux only.

* Uses "strace" for file operations and checks that only allowed files
  are accessed, and nothing from a Python installation at all.
Renamed "portable" to "standalone" mode.

* The new name more clearly conveys the goal of the mode, that is to
  create a binary that can be run without installation of Python at
  all.

* Also cleaned up cases, where it was referred to, but actually it
  was about embedding bytecode.
Renamed meta path based module loader.

* Nothing to do with "unfreezing" as understood in CPython terminology,
  which we now also have.

* To avoid confusion, esp. as now it's not only loading compiled modules,
  but also for "standalone mode" the extension modules bundled.
Changelog updates, added upcoming interface changes in 0.5.0
Debian: Build now depends on strace, updated gcc dependencies.
Debian: Recommend strace as well, it's needed for "--standalone".
More changelog updates
Added buildbot to use of used projects.
Need to run standalone tests in-inplace, so they can find their results.

Also expect success when executing the standalone programs, or else they
may break without us noticing.
Fix, standalone failed on Python3 unless UTF8 was the IO encoding, which need not be.

* Specifically inside pbuilder of Debian that is not the case, but there it
  should be ASCII, which parts of Python3 stdlib do not comply to.

* This is assuming that all frozen code conforms to UTF8, which won't be the
  case once we allow user code to be frozen as well. That is not yet possible
  though.
New stable release.
Merge branch 'release/0.4.7' into develop
New release cycle.

* Major version bump, because this is going to break user interface.