RetroSkill rule resets 1st level multiplier to x1 after gaining 2nd level

Skill multiplier is now correctly applied for first character level.
Issue#: CODE-2206


git-svn-id: svn+ssh://svn.code.sf.net/p/pcgen/code/Trunk@21577 ef53c05b-3124-4d59-ae7d-fe3273f42be7