Fix missed file in fabbfdb0.
Add Google Test and Google Mock

Enabled with --enable-google-test, configure the location of the sources
with --with-gtest-root, --with-gtest-headers, --with-gmock-root, and
--with-gmock-headers. The latter isn't necessary if the headers are
installed in /usr/include and the sources in /usr/src as the Debian
packages do.

This is a first-pass and needs to be made a bit more sophisticated later.
It might also be worthwhile to extract it into an m4 macro.
Modify gtest/gmock tests to work around demented test implementation in Debian
Fixed kvp-value delete

Delete wasn't being called properly due to bad template resolution.
Implement KvpFrame in C++ using std::vector

KvpFrame was implemented using GList. Given the current desire
to distance ourselves from glib and acquaint the project with
C++, the standard library thereof, and boost libraries, KvpFrame
has been replaced by an implementation that uses a std::map<
const char *, KvpValueImpl *>.

There were some cases of the KvpFrame's glist being accessed
directly. A new API to help callers access the KvpFrame's contents
systematically by providing a list of keys has been created, and
call sites of the GList code have been updated.

Another deprecated #define was found and removed (kvp_frame_set_str).
Update CMakeLists after recent file addition
Build glib gtester based tests under check_PROGRAMS, run under TESTS

Instead of TEST_PROGS. This has two advantages:
* By deferring the builds until make check any prerequisites, especially
in test-core, are already built regardless of overall build order.
* The output of these tests is logged and the success or failure
included in the make check summary instead of adding their rather verbose
output to the stderr.
Fix stray left-over line which prevented most of the engine tests from running.
Added quotes to gtest section in configure.ac

Without these quotes, the error messages can be confusing in the case that
variables contain spaces, and, more likely, when the variables are empty.