add call syntax and emit constrained prefix

[dsyme]

No description provided.

[dsyme]

• Fixes syntax for f<^T> so no space required
• Fixes syntax for TypeProvider<@"abc"> so no space required
• Add 'T.Foo
• Add ^T.Foo
• Emit constraint call

However there is some kind of bug in codegen that causes failure at runtime and the test I've added fails with

System.MissingMethodException: Method not found: '?'.
   at <StartupCode$FSI_0001>.$FSI_0001.main@()

However we can merge this I think, it's basically good and on the right track.

TODOs for testing to add to the list

• Get the test I've added working
• Test all of the above
• Test op_Implicit and op_Explicit

[vzarytovskii]

Is this temporary?

[dsyme]

Didn't mean to commit it, but I guess it's useful for me as can quick compile using command line to look at cidegen with lildasm using net4.x. Haven't found an easy way to do this on netcore