New weapon sway/bob features

Firstly, this adds two new sway speeds: "motion" and "jump" sway, which apply when the player moves (e.g, moving on a slope/lift, or (un)crouching) and jumps up/down respectively. Secondly, this also adds options to bob the weapon up/down while standing still, to give the effect that the player is "breathing". The DECORATE weapon property counterparts are also added for these new features.

With the addition of the new motion/jump sway speeds, to avoid ambiguity, I also renamed cl_swayspeed to cl_viewswayspeed since this particular speed only applies when the player looks around. Although this CVar existed since 3.1, I believe that renaming this particular CVar should be okay because it's purely a cosmetic effect that doesn't have any impact on gameplay.