ENH: fix find program to look for .com and .exe correctly and not return files with no extension on windows

ENH: Add documentation on the problem with system wide path for looking up dynamic libraries. STYLE: Fix trailing white spaces

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