should be able to alter a tag

[masukomi]

i have "question" and "questions" i want to get rid of "questions" and replace it with "question" (or anything else)

• should search for existing tag with "new" name.
• if the tag already exists then events_tags needs to be updated to use the existing tag id

Questions

• should this be interactive? E.g. "what tag should i get rid of? [input] What tag should i replace it with? [input]"

Misc

could be implemented by adding the new tag to everything with the old tag then deleting the old tag.

would need to implement the ability to kill and old tag.