[R-Forge #1957] Optional Arguments for Printing #645

Submitted by: Yike Lu; Assigned to: Nobody; R-Forge link

It would be nice to have a few simple optional arguments for displaying/printing data.tables, for example:

1. Turn off row numbers,
2. Turn off smart table wrapping
3. Force print all entries
4. Put spaces between "by" groupings for higher groupings... e.g. DT[, sum(x), by=list(a,b,c)] prints as

a b c V1
1 1 1
1 1 2

1 0 3

2 1 1
2 1 2
2 1 3

Perhaps a depth variable can be specified here.

5. underline/underscores for column header, horizontal bar to separate key and nonkey columns.