BUG: Trying to get testDynamicLoader to work on Solaris and SunOS, where current directory is not lookup when doing dlopen

ENH: Make sure that we find the proper symbol and not the one that start with _. STYLE: Remove an old style cast

BUG: Including file within a namespace{} is dangerous(unless symbols are within an extern C). Also update documentation about special case for MacOSX

ENH: Adding kwsys implementation for a DynamicLoader class. Copy from itkDynamicLoader, with patch from cmDynamicLoader