Fix Lancing Steel hit rate calculations

[Lilylicious]

Fixes #1736

Description of the problem being solved:

Lancing Steel was using a DPS multi for its 60% less damage with subsequent hits. This meant that it was treating the skill as if it was hitting 60% less often, rather than doing 60% less damage.

I've split the modifier into two. The DPS multiplier now scales with projectile count, while a less damage modifier is added which is 60% multiplied by the percentage of projectiles affected by the modifier (all except first)

Link to a build that showcases this PR:

https://pobb.in/mMOVEN0vLM9y
Difference is most notable in the max poison stacks, which should not be affected by less damage dealt, and in bleed calculations where it has a major impact.