Short term:

- migrate entropy.db per-thread resources to TLS (threading.local())
- eit cache clean
- drop all the EntropyCacher.CACHE_IDS

- conditional deps:
  enabled with ETP_PORTAGE_CONDITIONAL_DEPS_ENABLE
  Test package generation and entropy client behaviour
  (both direct and inverse dependencies calculation)

- rewrite entropy.Security() to be O(1) (dump sulfur first)


 Long term:

 - move variables away from etpConst
   (to SystemSettings || Client || Server as static methods)
 - Python 3.3+ support

 - [2014] remove repositories parsing from repositories.conf
          also see _conf_add_repository(), _conf_remove_repository(),
          shift_repository()
 - [2015] remove non-ini repositories parsing support from repositories.conf.*
 - [2015] remove repositories parsing from server.conf