Pilot packages for Seal of Approval

Three packages proposed for Seal:

- nc:  By Toby, adds regular expressions to data.table
- tidyfast: By Tyson, implements dplyr-like verbs with only data.table as a dependency
- dtplyr: By Hadley, adds data.table backend to dplyr verbs.

Merging of this PR by a maintainer will consistute Approval on these three packages!

Seal_of_Approval.md

@@ -8,8 +8,14 @@ To add your package to this list, please [submit a Pull Request to The Raft](htt
 
 ## Extension packages: Add to the internal functionality of `data.table`
 
+- [nc](https://github.com/tdhock/nc): Named capture regular expressions for text parsing and data reshaping.
+
 ## Application packages: Use `data.table` to accomplish a particular task or analysis.
 
 ## Bridge package: Translate data.table syntax to different syntax or provides helper functions for transitioning between `data.table` and another object type.
 
+- [tidyfast](https://github.com/TysonStanley/tidyfast): Fast and efficient alternatives to tidyr functions built on data.table
+
+- [dtplyr](https://github.com/tidyverse/dtplyr): A `data.table` backend for `dplyr`
+
 ## Partner package: Not necessarily directly connected to `data.table`, but deliberately follows the [core philosophies of `data.table`](https://github.com/Rdatatable/data.table/blob/master/GOVERNANCE.md).