Add duration (by default) to tblock command

[Lpsd]

Updates the .tblock command, adding an extra argument for block duration. The argument is optional and defaults to "5d" (5 days).

Usage: .tblock <userid> <duration>

Duration is a string e.g 1 day, 1d, 2 months, 60s

Adds a command to check if user is blocked, .tcheckblock <userid>

[xLive]

I would use Discord timestamp format instead of fromtimestamp, but other than that, LGTM

[theSarrum]

Let's make the changes that @xLive suggested.