allocwrl.icn: Program to display storage allocation in VRML

This program produces VRML 1.0 worlds with shapes representing storage
allocation in the program it monitors.

The structures normally are laid out in the x-z plane along a path with
the shapes rising in the y direction. The size of the allocation
determines the size of the shapes.  The same shape is used for all
allocations, but the color indicates the type of allocation.

The kinds of allocation modeled are given by masks:

     structs         only allocation related to Icon's structure types
     blocks          all allocations in the block region
     non-structs     all allocations except for structures

The supported shapes are:

     cylinder
     cuboid
     cone

In this version, if the path file is exhausted before the SP terminates,
the path file is closed and reopened.