Use tibble::print.tbl() for printing

[krlmlr]

now only need to override tbl_sum(). Also fixes tests.

Closes tidyverse/dplyr#2749.

@hadley: Could you please review (and enable reviews for this repo)?

[hadley]

Can you keep the extra spaces so the colons line up?

[krlmlr]

Now aligning colons by adding space before them. Let me know if you prefer adding space after the colon, like in the original output.

[hadley]

I prefer space after colon

[krlmlr]

Now aligning colons by adding space before them. Let me know if you prefer adding space after the colon, like in the original output.

[krlmlr]

Do we need to keep this?

[hadley]

I don't think so

[krlmlr]

I don't have permission to merge.

[javierluraschi]

@krlmlr See tidyverse/tibble#285, dplyr used to trigger tbl_desc() for computing the headers of a tibble, but now we rely on tibble itself, which is great; however, tibble calls nrow and dim which is subclassed in some backends to trigger a full table scan.