It allows tools which expect version in form major.minor to work
correctly even in case when pmdk is downloaded as zip archive.

This patch also removes '%d' from GIT_VERSION file. This placeholder
was filled with name of the branch only for the HEAD of a branch.
This means that GIT_VERSION of a selceted revision had different content
(either only commit hash or commit hash + name of the branch) depending
on whether selected revision was HEAD of the branch or not. Different
content of GIT_VERSION affected hash of the archive (and caused problems
with vcpkg in the past).

Version with two dashes (like 1.5-19-gb8f78a329) confuses rpmbuild in
recent Fedoras, which makes it generate uninstallable -devel packages
(libpmem-devel doesn't have Provides: pkgconfig(libpmem) tag, which
doesn't satisfy Requires: pkgconfig(libpmem) in
libpmem[obj|blk|log]-devel).

There are many problems:

On Linux we were using git commit id of the parent repository if
zip/tar.gz package was uncompressed inside of git repository (and
this is the case for Fedora).

We can't rely on GIT_VERSION for releases, because its contents depends
on state of the branch the tag was created from.
This file contains all refs that point to the tagged commit, so
immediately after 1.4.1 release it contained both "1.4.1" and
"stable-1.4", but after merging the first PR to "stable-1.4" branch it
contained only "1.4.1". This means that the checksum of the released
version changed! This is why vcpkg build from master fails now (it
contains initial checksum).
The fix is to remove the automatically filled GIT_VERSION file and add
static VERSION file before the release and revert this commit after.

Version reported by debug libraries was empty if libraries were built
from directories other than / and /src.

On Windows reported version for point releases was wrong.

Utilizes 'export-subst' attribute to provide source version info
in GIT_VERSION file for tarballs generated using git-archive.
The output format is different than for git-describe, so it must
be parsed to extract the tag or commit hash.
This is to make sure the tarballs autogenerated by GitHub
contain the information about the source version.

If the build scripts have no access to GIT, then the source version
cannot be determined (git describe) and the version string is empty.
This patch changes the default to "UNKNOWN VERSION".

Ref: pmem/issues#578

When building NVML from a source tarball, it is not possible to obtain
the version number via 'git describe' and '1.0' is used in such case.
This patch allows to pass the version string as an argument to
msbuild (/p:SRCVERSION=...) and override the default.

accept tags in format <major>.<minor>-<anystring>

All libraries + pmempool tool should have correct version metadata

Generate only one srcversion.h file that is explicitly included by other
projects.  This forces re-compilation of all the dependant files whenever
SRCVERSION definition changes.
Add a separate 'srcversion' project with custom build step to check
source code revision at each build, and re-generate srcversion.h file
if necessary.  The trick with setting __NON_EXISTENT_FILE__ as the output
of the custom build step provides that SRCVERSION.PS1 script is executed
for each build.

This patch sets SRCVERSION on windows based on git describe

Update all copyright headers:
- remove "(c)" string
- replace "Intel Corporation" with
  "the copyright holder" in the 3rd clause
- update copyright date to 2016

Because tests and examples are now compiled and linked using both c
and c++ compilers a special makefile variable was required to identify
the language. It was named LANG - unfortunately that conflicts with
locale settings, the new name is COMPILE_LANG.

This patch introduces C++ for libpmemobj. For now
it includes 'resides on pmem' template property
class and a persistent smart pointer.

These functions use non-temporal instructions.

Ref: pmem/issues#12

- rename typdefs: PMEMblkpool, PMEMlogpool, PMEMobjpool
- split libpmem into libpmem, libpmemblk, libpmemlog, libpmemobj
- rename trn => obj
- add benchmark building to make check target
- change functions _map() to _pool_open()
- update scope tests
- each library now has the environment variables:
    PMEM_LOG_{LEVEL,FILE}
    PMEMBLK_LOG_{LEVEL,FILE}
    PMEMLOG_LOG_{LEVEL,FILE}
    PMEMOBJ_LOG_{LEVEL,FILE}
- each library now has the *_check_version functions

[@andyrudoff made some additional changes to this commit:]
- remove superfluous nested includes
- remove extraneous comments (leftovers) in headers
- add calls to force library linking in traces_pmem unit test