all: put the duration and begin into conditions

The duration and begin are now part of a condition. The vpz of vle
packages are updated in order to take into account this new feature.
all: make use of the new functionnalities

Using VleUtilsConfig.cmake, dynamics are build and linked
to pkgs that are declared directly into the cpp file.
vle.examples: fix generator dynamic building

On win32, the targets order must be respected for the ompiling process
(GeneratorWrapper must be the last target). Otherwise some symbols are not
found.