Chain Spawnpoint / Parameters

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* Mace point mapthings have been slightly modified.
   - MTF_AMBUSH: bigger luke theory (has no effect on custom mace, different effect on spring mace)
   - MTF_OBJECTFLIP: flips the objects, but nothing else - just so it doesn't look out of place in gravflip sections
   - MTF_OBJECTSPECIAL: keeps it from attempting to play swinging sounds
   - angle: tag of controlling linedef
   - parameter: number of "spokes" minus one - for example, a parameter of 2 results in 3 equidistant maces rotating around the same point.
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* Mace linedefs have been significantly revamped.
   - line dx: number of chain links
   - line dy: speed (in FU)
   - frontside floor height: Pitch (in degrees; how much it "tilts" over - Yaw influences the axis it's tilting on)
   - frontside ceiling height: Yaw (in degrees; rotation of entire thing on xy plane)
   - frontside x offset: Phase (in degrees; how far it is through the rotation cycle)
   - frontside y offset: "Minimum chainlink distance" setting - if less than zero, the absolute of that many chainlinks will not be spawned from the center outwards, for if you want stuff to not be in a wall. Doesn't affect the head of the chain at all, since otherwise what's the point? :V
   - backside floor height: Pinch (in degrees; 0 if no backside; essentially makes rotation conical instead of wheel-like)
   - backside ceiling height: Roll (in degrees; 0 if no backside; rotates on the axis of the spinning - identical to Phase for spinning maces, but useful for rotating swinging maces as opposed to just offsetting them)
   - backside x offset: Number of "antispokes" (0 if no backside; makes that many spokes not exist so you can put another mace/chain type in there instead; for combo mace/chain instead turns them into chains directly)
   - backside y offset: Width (in number of extra chains per side; 0 if no backside; creates a "skiprope" arrangement)

   - ML_NOCLIMB: for chains and chain-mace combos, allow for player control of yaw through strafe keys
   - ML_EFFECT1: replacing the seperate mapthings, this makes a mace type swing instead of spin.
   - ML_EFFECT2: for all spokes of the mace wheel ending in maces, make the chains out of the mace type (inverted for firebars)
   - ML_EFFECT3: spawn a bonus mace type at the center(s) of rotation
   - ML_EFFECT4: don't clip inside ground
   - ML_EFFECT5: always think/visible (maces without this have a pop-in distance effect)
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* Mapthing 1104 represents both spinning and swinging maces from prior versions of SRB2.
* Mapthing 1105 has gone from being a swinging mace variant to a combination of chains and maces in a single unit, provided the number of "spokes" is greater than one.
* Mapthing 1105 has gone from being a swinging chain variant to a vertical spring-on-a-ball-on-a-chain. Yellow by default, apply MTF_AMBUSH to turn into a red spring.
* Mapthing 1107 represents both spinning and swinging chains from prior versions of SRB2.
* Mapthing 1108 (hidden sling) is completely untouched except to port over 2.1's functionality to the new backend.
* Mapthing 1109 is a Mario castle-level style firebar. This inverts the functionality of ML_EFFECT2 on the tagged linedef.
* Mapthing 1110 is a free slot should we want to implement another type of base-game mace.
* Mapthing 1111 is a custom mace. Use the linedef's frontside texture slots to identify a macetype mobjtype, then use the backside texture slots to identify a linktype mobjtype (defaults to MT_NULL if no backside).
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