* Add a "moveforward" param to P_InternalFlickySpawn, which controls whether...

* Add a "moveforward" param to P_InternalFlickySpawn, which controls whether to spawn the flicky a little in front or behind of the object making it.
* Expose this via additional upper-16-bits flags of A_FlickySpawn.
* Use this to make Snailers not spawn their flicky inside the wall they're attached to.
* Make the behaviour of Egg Capsules more consistent mechanically regarding the flicky spawning, using the above as one relevant element.