use isfinite, isnan, isinf from std::

* fix clang depracated finite
fix string format warging

format specifies type 'int' but the argument has type 'size_type'
fix name of make, mingw32-make
skip the build of qucs-filter-v2 on Darwin

The incomplete filter-v2 only builds withs -stdlib=libstc++
On OSX clang defaults to libstc++. \fixme
fix qt library name, test for platform
use OutputDebugString that expects a const char*

See:
http://stackoverflow.com/questions/1333527/how-do-i-print-to-the-debug-output-window-in-a-win32-app
fix dynamic loader Windows, CMake and Autotools
cmake: add vcresistor.va