Starpost config additions

A couple of changes that I think improves mappers' lives ever-so-slightly with regards to starposts.

• Allow using the Parameter field to denote starpost order instead of adding multiples of 360 to the angle.
  • For starpost counts above 16 (honestly, this is probably only relevant for Kart), multiples of 360 can be combined with Parameter. You'll have to start Parameter back from 1, NOT 0, to sequence properly.
    • Example: your 16th starpost would be Param=15 Angle=0. Your 17th starpost would be Param=1 Angle=360.
  • This is backwards-compatible with current maps as long as nobody's leaving Parameter set on starposts by mistake (which is pretty difficult to do, since new things are always placed in ZB with a Parameter of 0 until changed).
  • Incrementing a separate field by one seems like much less headache than constantly trying to add up multiples of 360 in your head. Even if you have a ton of starposts, you should only ever have to go up to one or two 360 multiples if combined with Parameter, which is much easier to keep straight.
• If a starpost has the Ambush Object Special flag set, spawn players at the starpost's exact location instead of the X/Y coordinates they touched the starpost at.
  • Rationale: this can be used for starposts that are placed near hazards or ledges to fix scenarios where a player would respawn directly onto said hazard.
  • This shouldn't affect maps unless people have left the flag on starposts for no reason, which is much easier to do than the Parameter issue since IIRC flags are kept on new things. This can cause issues if a starpost is in an activator sector used as an FOF.

Sample WAD: newstarposttest.wad The row of starposts is sequentially defined by Parameter, and the flower bed starts at the 17th starpost where 360 is added to the angle (and it restarts Parameter at 1) to allow more than 16 starposts with this method. The 17th starpost (the first one at the flower bed) has Ambush checked, so the player will respawn in the middle of it.