need a safety valve on `max_area`

[mdsumner]

yeeesh, don't run this

# r1 <- raster::setExtent(raster::raster(volcano), raster::extent(silicate::inlandwaters))
#clear3d();shade3d(as.mesh3d(DEL(silicate::inlandwaters, max_area = 0.001), z =r1))
#aspect3d(1, 1, 0.5)

that should trigger a check, range(x_)/sqrt(max_area) etc.

[mdsumner]

start with 1e8 triangles max, in a89fb56

[mdsumner]

Done