Add xULN chart.

[samussiah]

• x-axis: study day or study visit
• y-axis: standardized results (xULN)
• measures:
  • Bicarbonate Blood Urea
  • Nitrogen
  • Calcium
  • Chloride
  • Phosphorus
  • Potassium
  • Sodium
• customization: add reference line at ULN