Add specific permissions for hollow shapes and add //platform [block]

Adds the following permissions:

worldedit.generation.hcube - Permission to allow generation of a hollow cube.
worldedit.generation.hcylinder - Permission to allow generation of a hollow cylinder.
worldedit.generation.hpyramid - Permission to allow generation of a hollow pyramid.
worldedit.generation.hsphere - Permission to allow generation of a hollow sphere.
worldedit.generation.platform - Permission to allow generation of a platform.


Adds the following commands:
//platform [block] - Creates a 1x1 platform underneath the player. By default, the platform is made out of glass.