GNU R Cubature over Polygonal Domains

 Numerical integration of continuously differentiable
 functions f(x,y) over simple closed polygonal domains.
 The following cubature methods are implemented:
 product Gauss cubature (Sommariva and Vianello, 2007,
 <doi:10.1007/s10543-007-0131-2>),
 the simple two-dimensional midpoint rule
 (wrapping 'spatstat.geom' functions),
 adaptive cubature for radially symmetric functions via line
 integrate() along the polygon boundary (Meyer and Held, 2014,
 <doi:10.1214/14-AOAS743>, Supplement B),
 and integration of the bivariate Gaussian density based on
 polygon triangulation.
 For simple integration along the axes, the 'cubature' package
 is more appropriate.