Use helper function to deal with nil arguments to formatted strings.

This fixes using the trace functionality to explore the decisions that
Ovale is making.

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@858 d5049fe3-3747-40f7-a4b5-f36d6801af5f
Fix buff/debuff conditions broken in commit r834.

This fixes BuffPresent, BuffExpires, BuffRemains, BuffDuration, NextTick,
Ticks, TicksRemain and TickTime to return the correct results again.

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@859 d5049fe3-3747-40f7-a4b5-f36d6801af5f
Code consistency.

git-svn-id: svn+ssh://svn.curseforge.net/wow/ovale/mainline/trunk@860 d5049fe3-3747-40f7-a4b5-f36d6801af5f