FR: Possible applications for curves

@Baezon observed that we should collect desirable uses for the new curve system in an FR or something, so here we are.

- Particle length over lifetime (for particles that have that, obviously)

- Laser attributes over lifetime
- [x] Width
- [x] Length
- [x] Alpha

- Beam attributes over lifetime
- [ ] Width
- [x] Alpha

- Projectile attributes over lifetime
- [ ] Speed
- [x] Homing turn rate
- [x] Damage

- [x] Shockwave size over lifetime

(_- Random ranges in particles.tbl_) this one is apparently nonviable

- Cone distribution for cone-type particle effects, as an alternative to +Deviation (that is, treat the cone direction as 0, and 180 degrees from the cone direction as 1, and use the curve to determine spawn probability across that range)