To draw the progress bar, XPGlobesOverlay.drawTooltipIfMouseover() uses
Experience.getXPForLevel(), which threw an IllegalArgumentException when
asked about level 1. This change shifts the XP_FOR_LEVEL array over by
one, so that XP_FOR_LEVEL[0] is the XP required to reach level 1 (i.e. 0),
rather than the XP required for level 2.