The admin should be able to choose which features of moin will be protected by textchas
Currently, if one enables textchas, these are automatically used in many features of moin (user registration, page edits etc).
Some admins could be interested in having textchas only for some features (e.g. user registration).
Proposal: add a configuration directive (textchas_enabled_action?) to choose which actions should use textchas (default: all)