win32: update portage

- fix the building of vle.dll using flag VLE_DLL.
- remove static vle library (remove BUILD_SHARED_LIBS option).
- build a libgvle.dll fo win32.
- template: use static boost libs.
- template: add cmake macro for test building.
- Define the cmake FindPackage scripts : VLE, VLE_DEPS, GVLE, GVLE_DEPS.
- Modify gvle.pc to find libgvle for win32.
win32: split gvle.exe and libgvle.dll

To simplify the CMakeLists.txt scripts, we build a shared library
libgvle.{dll|so} on both POSIX and WIN32.

We move the program gvle.exe into src/apps/gvle directory. gvle.exe use
libgvle.{dll.so} at runtime.
win32: fixing Gtk problem with dll and application

With mingw32, gvle.exe (only depends to libgvle.dll and libvle.dll), the
Gtk::Window is not displayed if the Gtk::Main loop is in gvle.exe and the GVLE
class is in the libgvle.dll. This seems to be a bug in Gtk since with have no
problem to run gvle.exe statically linked with libgvle. To fix the problem, we
introduce the static start function in libgvle.dll which wraps the Gtk::Main
loop into libgvle.dll. Now the gvle.exe application have only a call to this
function.
win32: build static libraries for vle and gvle

To achieve a better compatibility with porting linux and windows
application, we generate static and shared libraries for vle and gvle.