Fix conversion and charges being negative

[QuickStick123]

Fixes #5097

Description of the problem being solved:

Negative charges and conversion is being fixed in the next update.

The self curse bug wasn't a problem in PoB

Fixed a bug where having negative values of damage conversion would grant extra damage of the initial damage type.

Fixed a bug that allowed the total value of minimum power, frenzy or endurance charges to go negative, which could cause skills to act as if players had more charges than they actually did.

Steps taken to verify a working solution:

• Negative charges result in zero discharge damage
• Negative Conversion doesn't increase damage

Link to a build that showcases this PR:

https://pobb.in/tpMBPfRjjSiK

Before screenshot:

After screenshot: