Fix double-click causing multiple requests in search.js

All buttons that cause e.g. ajax and changes to the db have to be disabled on the first click, so that someone with a slow connection double-clicking them does not cause harm.
Fix double-click causing multiple requests in classification.js
Fix double-click causing multiple requests in billing.js

Because the proe-creation-button doesn't use ajax, we can't determine when it's finished. So just disabling the submit for some seconds on each click.
Remove unused global function notIn()
Fix double-click causing multiple requests in meku.js
Fix double-click causing multiple requests in reset-password.js
Fix double-click causing multiple requests in subscriber and user management
Fix classification-form email-address select2 showing [object Object]

Also, don't show deleted users/accounts in email dropdown

oops
classification-form: Keep register button disabled while autosave ajaxes are in progress
Don't allow username to contain crazy characters
Show/generate/save account.apiToken if root