Directory white list running ctags

[dyong0]

Hi, I'm using easytags with automatic update. But every time I saved some files in home directory, it was making my laptop stuck. So I just wrapped UpdateTags command with a function, which is checking where I'm running the command and rejecting other than entries on my white list.

But I thought there's someone like me, I've raised this issue and created the pull request of this feature. #160