move code of RC plugin to core

Rest of RC plugin code is moved to core bit by bit and the rc_plugin is removed.

Note: there is a small difference in RC costs that starts with first RC delegation soon after block 67.1M and slightly increases up to HF26 where it starts to get closer to old values. Previously the code that calculates extra cost of RC delegation was in signal handlers wrapping around the call to evaluator, so it was called regardless of hardfork state, now it is embedded in evaluator, so it only triggers for effective delegations (starting at HF26 - dead delegations prior to HF26 no longer carry extra cost). It could be corrected, but the code would look unnatural, so the new values were accepted (using the fact that RC is still not part of consensus).

Needs test-tools!149 (merged) and schemas!48 (merged)

Next stage will be to move still isolated code inside temporary on_pre/post_apply... routines into specific operations in core code. Note that due to isolation code being hardcoded it is currently not possible to "run advanced benchmark without plugins", meaning measurements on operations that emit virtual ops will always be broken (until at least vops are moved away from isolation code).