Small refactorings related to issue #367

TGT and campvis-core used to manually define flags that instructed their
code to export DLL symbols. However, CMake has a property called
DEFINE_SYMBOL that can automatically define export flags when necessary.
Refactor the CMakeLists of TGT and campvis-core to make use of it.

References #367

CAMPVis used a custom option, CAMPVIS_SHARED_LIBS, to determine whether
shared or static libraries should be built. This option partially
duplicated the functionality of one of CMake's standard flags,
BUILD_SHARED_LIBS. The two could get out of sync, and because CMake only
consults BUILD_SHARED_LIBS when deciding how to build a library target,
it was possible to get inconsistent and broken build configurations.

To prevent that, add BUILD_SHARED_LIBS as an option to CAMPVis' main
CMakeLists and replace all references to CAMPVIS_SHARED_LIBS with
BUILD_SHARED_LIBS. This makes BUILD_SHARED_LIBS the only flag that
controls whether shared or static libraries are built.

References #367

Data Inspector Jenkins Fix

I have fixed all of the Jenkin's errors but there was another thing in source/modules/randomwalk/processors/confidencemapgenerator.cpp which should be fixed but I think the variable in Line 207 may not be used anywhere but it is added to some object in create function. The only thing which I can do is to omit the confidenceMap pointer definition.

Fixed TrackballNavigationEventListener setting the window ratio of its CameraProperty being directly overwritten due to concurrent access.

Fix Cppcheck Issues

Itk Module Fixes

Itk Module Fixes

Fixed GCC warnings in ItkImageFilter (false positive). Removed ItkImageFilterKernel, as they throw even more GCC warnings and meanwhile CAMPVis has the GlMorphologyFilter processor doing the same much faster and elegant.

Fix Cppcheck Issues

Campvis Core Dll

* Fixed duplicate symbols of template specialized TextFileParser::readAndParseItems<TextFileParser::ItemSeparatorLines> due to forced inline

Campvis Core Dll

refs #377

Builds and runs fine so far, but no elaborate testing done yet. Compiler throws a bunch of C4275 warning, since sigslot:has_slots<> is used in exported classes but is itself not exported. While this is no direct problem for campvis-internal builds, it should still be fixed some time.

refs #377

Tgt Dll

refs #376

Added C4251 to the ignore list for MSVC warnings, occuring due to missing template instantiations of the standard library used in public interfaces of tgt and campvis code. Even though articles such as <http://support.microsoft.com/kb/168958/en-us> provide a clean solution to fix these warnings, I decided that exporting bazillions of std library templates is not worth the effort. As we do not plan to ship TGT without the rest to a variety of systems, the missing exports won't be a problem.
BTW: The original tgt library build scripts also deactivate the warning. :)

closes #376

Closes #387: LogViewerWidget now has a checkbox to select the minimum log level to display. Filtering is performed in widget. Checkboxes to enable/disable each log level, however, seemed to be overkill. If one really wants such specific filtering, he/she can use the filter text box.

Extended the DataContainerTreeWidget and its corresponding DataContainerTreeModel to support a second level containing the DataHandles of RenderData and ImageSeries items.

* Fixed bug introduced in 8a8f9bba: Mouse wheel handler was modifying wrong slices
* Updated README.md