#3962 suggestion for ! rather than not

[zobier]

slashtags suggest the use of ! instead of not for anti-tags, this doesn't make sense for words beginning with not e.g. nothing. This is a cosmetic issue only but suggesting someone use !hing if they disagree with hing doesn't make sense. Suggest picking some of the words from here <http://www.morewords.com/?not*> to exclude from this feature.