Three new primitives plugin for shell, spiral, gear

[PhilippePoupon]

Hello, I made three primitives plugins.
It is an evolution of plugins already existing for spirals and cylinders with more parameters.

There is a plugin for spirals with logarithmic spirals, an other one for gear and one to make shells.

Install into wings3d_2.1.5\lib\wings-2.1.5\plugins\primitives

zip file for 2.1.5 binary

zip file for sources