New special functions

• New atomic functions:
  • pbeta
  • qbeta
  • dtweedie
  • besselK (derivatives wrt both arguments)
  • besselI (derivatives wrt both arguments)
  • besselJ (derivatives wrt both arguments)
  • besselY (derivatives wrt both arguments)
• Adaptive numerical integration:
  • gauss_kronrod::integrate (one dimension)
  • gauss_kronrod::mvIntegrate (multiple dimensions)
• sdreport: Fix bug that caused bias.correction to break when
  parameter maps were in use.