* support set of keys to sign spork
* several addresses support in -sporkkey
* tests for multykey sporks
* command line option -minsporkkeys
* make spork active only after given number of signers
* use signature in spork hash calculation
* test for new and old spork messages interaction
* add multikeyspork.py to integration tests
* change test to have ability to distinguish default spork value
* require min spork keys number to be more than the half of the common spork keys number
* calc current spork value with majority of signers
* set test nodes time in integration test
* extract keyid from signed spork message directly
* change -sporkaddr option syntax to process several addresses
* codestyle fixes
* fix test comments
* codestyle fixes
* simplify CSporkManager::SporkValueIsActive
* Calc signature hash without signature field
* do not restore pubkey ids from cach
* Calc different keyids to check signature because not all sporks can be synced at moment
* codestyle fixes
* Fix CSporkManager::CheckAndRemove to use several keys
* codestyle fixes
* Correct processing of not actual spork6 value with GetSignerKeyID
