Review extension methods.

[gusty]

By adding a few attributes we add the possibility to use some methods from C# and F#. However in order to use them:

• From C# the method should not be generic. Also there is a problem if the method accepts an f# function, it will be tedious to use it.
• From F# the method should not have dummy arguments, though this is not a technical limitation, they can be used but add lot of noise.

Another issue is than when the containing namespace is opened you see many methods, some of them will not work in C# but it displays everything. I think that's really annoying but an alternative is to remove the extension attribute of the generic methods.

Perhaps extension methods belong to a different project, F# extension methods are already being defined in F#+ so for C# we can create a C#+ project and put them there, adapting the function arguments, there will be a lot of boilerplate code in that project but to the outside world will be clean.

[gusty]

Extensions method didn't prove to be useful, at least to me. In any case if this library will be used or eventually merged with FSharpPlus, there will be extensions in the individual modules (Seq, List, etc).

[gusty]

UPDATE

This library was merged with FSharpPlus and upgraded to use F# 4.1 where optional arguments are recognized, so the second issue mentioned is no longer an issue.

[gusty]

This issue was moved to gmpl/FSharpPlus#42