Remove words from user groups

[viegasfh]

First of all, thanks for implementing this tool!

I have just come across this tool and find it very useful for vocabulary building. However, by looking at the code I noticed that it only allows to add words to user groups 1 to 10, and it doesn't let add any more once the group is full. It would be nice to be able to empty or remove words from user groups once we have mastered. I came across an article that mentioned the possibility of creating 100 user groups. However, I believe that to be an old version, as it didn't require the use of -w option for words.

Once again, thanks for sharing this tool!