Refactoring test code. Test routines are being seperated out from "main"
functions so that they can be invoked from other places, added a "testall"
file which allows for execution of full test suite.  Also adding TESTEXPECT
macro to allow for test assertions that do not throw exceptions.
Added comment to point out failing tests
Minor tweaks to code layout
Changing namespace for tests from "Partio" to "PartioTests".
Also making some additional minor stylistic changes in
namespace use
Merge remote-tracking branch 'upstream/master'
- moving header files out of "namespace Partio" (leaving them
in was causing many compilation errors for the tests)
(WIP) - changing to a direct test of kdtree
removing data generation set generation logic, replacing with
individual tear up/down in each test function.  Adding tests
for other routines
Small addition to docs
Correcting and adding more tests
added tests with non-stl containers
Re-adding the old "kdtree" tests as tests for the
ParticlesSimple class.
cmake: Allow users to specify CMAKE_INSTALL_PREFIX

Check whether CMAKE_INSTALL_PREFIX is defined before overwriting
its value.  This allows users to specify an alternate install prefix
during the `cmake` invocation.

Signed-off-by: David Aguilar <davvid@gmail.com>
cmake: Do not hard-code the path to doxygen

Use ${DOXYGEN_EXECUTRABLE} instead of hard-coding /usr/bin/doxygen.

Signed-off-by: David Aguilar <davvid@gmail.com>
cmake: Allow out-of-tree builds

We were referring to a build directory that does not exist
when building out-of-tree.

For example:

	mkdir build
	cd build
	cmake ..
	make
	make DESTDIR=$PWD/DESTDIR install

The `install` step will fail because build/src/py/partio.py
does not exist.  Remove the src/ subdirectory in the path so
that the file beneath build/ is found.

Signed-off-by: David Aguilar <davvid@gmail.com>
Fix installation command copying generated python file from the wrong location
Fix GLUT include directory path handling
Fix Windows installation variant directory specification
Fix M_PI undefined on Windows by including the correct header
Merge remote-tracking branch 'origin/partioInstancer' into redpawfx
Merge remote-tracking branch 'fgochez/master' into redpawfx