Shaders create two pins for one input

[tebjan]

from vvvv/VL.Stride#589
ShaderFX Nodes behave confused Create 2 input pins for each input in the shader, one named nicely, that behave confused, one other named by shadername + property name ... this works correctly not a big issue ... because i just use the second inputs.

This is indeed a weird issue, it looks like the shader reflection returns two pins and we don't sift them out. needs further investigation.

[tebjan]

A test patch that shows this issue is in #70