Make the render work with older f#

[davidtme]

When using FSharp.Compiler.Tools you do not have access to:

• opening of static classes
• member _. - this is throwing an error but I can't find the documentation when this was added - quite hard to search for

this just add GeneratedCodeUtils to the functions and replace _. with this.

[cmeeren]

There is no opening of static classes in generated code. I don't think this change is needed.

Instead of this., you can use __. (double underscore). That works for older F#, and still signifies that it should be ignored.

[cmeeren]

I can't find the documentation when this was added - quite hard to search for

Not sure what you're after here.

[davidtme]

@cmeeren sorry, I think the _ problem was thrown me off and making me thinking it was a static class

[cmeeren]

Released in v0.2.6.