moves std::shared_ptrs to a new implementation
Advantages:
- you can dereference a weak_ptr directly. This will obviously segfault on a nullptr deref if it's expired.
- this is useful to avoid the .lock() hell where we are 100% sure the pointer _should_ be valid. (and if it isn't, it should throw.)
- weak_ptrs are still valid while the SP is being destroyed.
- reasoning: while an object (e.g. CWindow) is being destroyed, its `weak_ptr self` should be accessible (the sp is still alive, and so is CWindow), but it's not because by stl it's already expired (to prevent resurrection)
- this impl solves it differently. w_p is expired, but can still be dereferenced and used. Creating `s_p`s is not possible anymore, though.
- this is useful in destructors and callbacks.
* animation: Refactor AnimatedVariable
This commit decomposes the AnimatedVariable class into a base class
with the common attribute to all variable types and a templated derived
type containing strongly typed info on the type being animated.
Access to the typed version is perfomed using the visitor pattern. A
utility is provided to build a visitor on the fly using lambdas.
Adding a new type to be animated should just be a matter of adding the
typed in the list defined by the ANIMABLE_TYPES macro
The size of the commit is justified by the API change in the
AnimatedVariable class. No more vec(), fl() or col() method but a unified
value() method.
* animation: Remove visitor pattern
* animation: Fix coding style
* animation: Fix coding style
