Adding Enspell Damage Percent Multiplier Effect

[lefneer311]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

This adds enspell damage % multiplier calculations, including the base effect from RDM JA Composure to battleutils.cpp, wires up the augment for enspell damage %+, and adds the modifier entries to mod.lua and modifier.h.

Steps to test these changes

Switch to RDM main (level 50+), use an enspell, engage a target and note the additional effect damage
Activate composure, engage a target and note the additional effect damage is 3x (+200%)
Use !additem with the augment ID 899 for +enspell dmg % on items and equip them
Note the additional effect damage multiplier scale

[lefneer311]

Closing and resubmitting. Comment names are too long, it seems.

[Xaver-DaRed]

Do an amend. Search how to amend and force push.
Please stop closing and opening a new PR with the same changes.

[lefneer311]

Do an amend. Search how to amend and force push. Please stop closing and opening a new PR with the same changes.

Will do. I was avoiding a force push because of the files being modified. Thank you, @Xaver-DaRed! #9503 will be the last PR on this topic.

[WinterSolstice8]

force pushing on your own branch doesn't effect us so don't worry about it