utils: update the package API

- Remove the package singleton and provide a public constructor.
- Make the distinction of the source and binary package in the API using
  the enum type (PKG_BINARY, PKG_SOURCE).
- Add a package instance to GVLE.
- Add the argument curr_package to gvle modelling plugins.
- Output files are now generated into the current dir for vle and rvle
  and into <current_package>/output into gvle.
win32: rely on native compilation

- boost dll are used rather than static libs
- static vle libraries are removed
- cpack is modified for native compilation
win32: fix m_prefix path setting

m_prefix was initialized using HKEY_CURRENT_USER even if it is not set
win32: fix requirements for gtk+

gvle.glade required gtk+ version 2.24 whereas win32 binaries of gtkmm
provide gkt+ version 2.22
win32: fix missing VLE_APi export symbol

VLE_API symbol was missing for operator<< in ExternalEventList
gvle: fix missing output directory while running

when running a simulation from gvle, the output directory of the
current package is required
utils: fix test_package

- take into account the separation of binaries and sources
- add the boost/version.hpp include