This replaces the cmake options `WITH_NEW_OBJECT_TYPES` and
`WITH_NEW_SIMULATION_TYPE` with two experimental userpref settings:
* `use_new_particle_system`: Enables the point cloud type and the simulation editor.
* `use_new_hair_type`: Only displays the add-operator in the add menu for now.
Note, in the current state you can't do anything productive with the new particle
system or the new hair type. Features will be added step by step in the upcoming
weeks and months.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D8096
87ceff3d1b