COMP: Remove unneeded call to "cmake_policy"

Since calling 'cmake_minimum_required' with version X.Y.Z implies that
policy associated with version X.Y.Z will be set, this commit
removes the redundant call to "cmake_policy".

For more details, see [1]

[1] http://www.cmake.org/cmake/help/v2.8.9/cmake.html#command:cmake_minimum_required
COMP: Remove duplicated MacOSX platform checks

Since the checks are already done in "Common.cmake" that is included
from both "SuperBuild.cmake" and "UKFTractography.cmake", this commit
removed the duplicate code.
COMP: Remove redundant directory includes in ukf/CMakeLists.txt

Since the variable MODULE_INCLUDE_DIRECTORIES is passed to the macro
SEMMacroBuildCLI, there are no need to manually include the directories.

This commit removes the "redundant" call.
COMP: Remove unused CMakeLists.txt in SuperBuild folder

The top-level CMakeLists.cmake, based on the value of the
UKFTractography_SUPERBUILD variable, already conditionally includes either
UKFTractography.cmake or SuperBuild.cmake.

This commit removes the SuperBuild/CMakeLists.txt file that contain
code already existing in SuperBuild.cmake.
COMP: Simplify inclusion of SlicerExecutionModel package

Since the project makes use of SEMMacroBuildCLI macro, there is no
need to selectively integrate "GenerateCLP" and then manually include
the macro. By simply looking up the  SlicerExecutionModel package
and including the associated *_USE_FILE, all required macro will be
available.
COMP: Simplify how standalone/superbuild and extension case are differentiated

This commits enables the following cases:

* By default the extension will be built as a standalone project using
superbuild to download the required dependencies.

* Slicer extension can simply be built specifying
   -DUKFTractography_BUILD_SLICER_EXTENSION:BOOL=ON
   -DSlicer_DIR:PATH=/path/to/Slicer-SuperBuild/Slicer-build
   -DEigen_DIR:PATH=/path/to/Eigen-build
COMP: Consistently find teem library

Since the teem library provides a TeemConfig.cmake file if it is either
build as part of Superbuild or install on the system, it is sufficient
to use the "find_package()" call.

This commit fixes a configure error [1] by removing the extra call to
"find_library" that ended up finding the teem library installed on the
system.

More specifically, in the Slicer case, the Teem_DIR was used by the
previous call to "find_package(teem)" to find the teem library built by
Slicer.

Modules ended up referencing a mix of system teem library and Slicer teem
library.

[1] Configure rrror fixed by this commit:

8<----8<----8<----8<----8<----8<----8<----8<----
Cannot generate a safe linker search path for target ConvertVTK because
files in some directories may conflict with libraries in implicit
directories:

  link library [libteem.so] in /usr/lib may be hidden by files in:
    /home/jchris/Projects/Slicer-2-SuperBuild-Release/teem-build/bin
8<----8<----8<----8<----8<----8<----8<----8<----
STYLE: Use consistent indentation in all CMakeLists.txt
STYLE: Remove unused code from Eigen external project
COMP: Fix build error disabling Eigen Qt dependency

On system without Qt development libraries installed in a default system
location, Eigen couldn't be built.

This commit removed the Qt dependency by disabling the test depending
on Qt.
COMP: Update teem project to allow use of system teem.

This commit update the external project so that it conditionally
download and build teem.
COMP: Simplify management of output and install directories

This commit remove the Slicer specific settings from SlicerExectionModel
and ensure the project will be configured with the expected values. Then,
it is not needed anymore to overwrite the SlicerExecutionModel_DEFAULT_*
variable in the current scope.

This has been tested for both a SlicerExtension and a standalone built.
In both case the libraries are built where expected.
COMP: Simplify passing of variable to external projects

Instead of manually creating list of option to give to each project, this
commits removed redundant code and leverage the "mark_as_superbuild"
macro.

By specifying the ALL_PROJECTS value, we ensure that the option will be
passed down to all external projects.

By using "ExternalProject_Include_Dependencies", the CMAKE_GENERATOR
option will be automatically passed to each project using it. This commit
removed the explicit management of this parameter.

Finally, since the passing of the _DIR variable is already set by calling
"mark_as_superbuild" in each external project, this commit removed
the explicit management of these.
Merge pull request #28 from jcfr/simplify-buildsystem-and-fix-configure-errors

Simplify buildsystem and fix configure errors