* Handle all chain objects as a hnext/hprev chain.
* When removing mobjs with hnext/hprev, "repair the chain" (make the h links meet).
* Fix hidden slings, which I accidentially broke when I revamped maces the first time.
* Kill MF2_MACEROTATE. Not needed for anything anymore.
* P_MaceRotate now available to Lua to make up for it.
* Related: Made modifying hnext/hprev using Lua safer, so it keeps the reference counts in play.
* All Lua-originated sprite2 settings are now forced through P_GetMobjSprite2. Makes sense because of SPR2_JUMP, which none of the main characters have sprites for yet all use.
* Cleaned up P_GetMobjSprite2 to not set irrelevant, otherwise-unused variable.
Here's how it works: When a player walks off the
moving platform, it applies their pmomz once, and
then _keeps pmomz set_ so that the camera still
adds pmomz to its movements until they hit another
floor. This way, the camera doesn't jerk around.
Angles now go from 0 to 0xFFFF (360 degrees == FRACUNIT) instead
of using a full UINT32. Lua only has one number type, so signedness
gets in the way of using angle_t directly. This handling of angles
matches up with how ZDoom ACS scripting and the like does it.
I also changed all the integer casts and pushes of fixed_t to
their own macro in preperation for possible future seperation.
