Feature request: Convert between CIDR and subnet masks

**Is your feature request related to a problem? Please describe.**
I work with network appliances in my day job and I have to be honest, I'm a big dummy when it comes to remembering the comparisions between CIDR and the subnet mask. The appliances I work with sometimes accept the CIDR while other times will only accept the subnet mask, so having a tool to calculate the appropriate counterpart would be valuable.

**Describe the solution you'd like**
Add an operation which converts between the CIDR and subnet mask. It would be nice if the "Parse IP range" operation would also accept masks in addition to the CIDR.