add a DB table for handling new registrations
add new config file for registration
begin implementing a registration API
rename registration URLs config to plural
continue registration API

* actually create account
   * change DB table users:
      'joined' column is now TIMESTAMP,
      DEFAULT CURRENT_TIMESTAMP
* implement POST-registration URLs
registration: hash password
require password to be specified 2x on registration
Merge branch 'master' into registration
successful registration: delete registration session
add missing code line from last commit
fix syntax error
POST registration: fix param order
POST registration changes:

* do not POST password
* also do not POST useless data such as token, ...
* correct parameter names
implement new config: USER_NAME_REGEX
implement new config: PUBLIC_REGISTRATION

Registration of new users can now be restricted
to users with a special privilege.

* add new privilege
* add and document config
* check user when initiating a registration
more user name restrictions

Implement lists of forbidden and reserved user
names (reserved names may only be registered
by mods, forbidden names cannot be registered).
remove obsolete parameter from validateLogin
fix: chaptcha token revealed

The chaptcha token could be obtained by using
a template variable. Replaced the variable by
the registration session ID, which was missing.
Merge branch 'master' into registration
add SQL file for new DB table