Versioning does not work across compilation units

[AzothAmmo]

When registering a type, version information is stored in two places:

1. a static member variable for a specialization of Version<T>
2. inside the static object (global singleton) StaticObject<Versions>.

When saving a type, we currently try to get its version number by looking at the member static variable. When loading, we access the StaticObject. This means that when something is versioned in one compilation unit, it won't be available via the specialization of Version<T>, since we never instantiate the class.

See https://groups.google.com/forum/#!topic/cerealcpp/vBYPUzGB9Mw for more information.

[AzothAmmo]

Possible ways to fix:

1. Make saving utilize StaticObject<Versions> instead of trying to read the specialization variable. Seems to work in initial tests across compilation units/shared libs.
2. Something akin to how we register things for polymorphic types to try and force a type to get instantiated so that it is properly exported, probably would require Possible to use with windows dll files #113 working properly.

[AzothAmmo]

May still be broken on Linux, see: https://groups.google.com/forum/#!topic/cerealcpp/u0GrjJCUJts. Can likely be fixed by applying changes seen in pull request: f29728b

[AzothAmmo]

Should be fixed on branch issues_113_137, will be merged into develop soon.

[AzothAmmo]

fixed on develop (6e41ed8)