v2.1812

  * use portage cache as binary download location
  * refuse to perform some actions if no package name is given (install/uninstall/force-uninstall/search)
  * merge vasile's modes (binmode/mixedmode/srcmode) into sisyphus (hybrid options)
  * implement hybrid options :
    * allow installing new packages using binaries and/or ebuilds
    * allow uprading the system using binaries and/or ebuilds
    * binaries will be used by default if they exist and their USE flags will match (aka binmode)
    * binaries will be used to satisfy ebuild dependencies if they exist and their USE flags will match (aka mixedmode)
    * ebuilds will be used if binaries don't exist or their USE flags will not match (aka srcmode)
  * refactor some code for better readability
  * speed up dependency resolution when using hybrid options
  * add support for next (testing) repository