Earning subscriptions introduced (unfinished):

Earning subscriptions introduced (unfinished):
- Generic support (unfinished admin/member scripts) added for extra earnings on
  a "subscription" basis. The user can (or shall when finished) see how much
  he/she earned per "earning subscription". This whole data table is now cached,
  other user_earning will follow
- Extension ext-forced continued, reload lock and minimum stay moved to
  campaigns
- Fix in inc/db/lib-mysql3.php for badly named variable (now: $isAlterIndex)
  which could cause many ALTER TABLE commands to fail
- Other minor improvements