Adds text to the influencebar.

Usage:
/btinf help - Show help
/btinf show - Show current formatstring
/btinf set - Show possible variables to use in formatstring
/btinf set <formatstring> - Set the formatstring
/btinf reset - Resets the formatstring to default

Possible values to use in BarText (Influence) formatstring:
[inf] = Current influence
[infmax] = Maximum influence for this level
[infp] = Current influence in percent for this level
[area] = Current area name
[zone] = Current zone name
[npc] = Name of npc that handles rewards