Support @using static

[Jeffrey Drake]

I have a number of utility functions that would be very handy to be imported using something like

@using static ....

The functions would be available in actions.

[John Gietzen]

You should be able to do this:

@using { static string }
@using "static DateTime"

a = x:. &{ IsNullOrEmpty(x) };
b = "now" { UtcNow };

[Jeffrey Drake]

I can confirm that this works great. Thank you.