Documentation of return types for line!() and column!() is inaccurate

[daboross]

http://doc.rust-lang.org/nightly/std/macro.line!.html states that the macro will return a usize, where in reality it returns u32.

Example: http://is.gd/pOkE5x.

This same problem exists for column!() as well: http://is.gd/4a0T9U. Documentation at: http://doc.rust-lang.org/nightly/std/macro.column!.html.