RSKIP-203: getCallStackDepth Precompile method

I’ve written a new RSKIP that proposes to add a method getCallStackDepth() to a new Environment pre-compile contract. The new method retrieves the current depth of the EVM call stack. To summarize, the objetive is to allow batching in intermediated transaction execution solutions such as Enveloping and the Fast BTC Bridge. It basically allows users to prove that a transaction has been executed in certain agreed conditions, including gas limit and stack space. You can read the RSKIP here.

While I do like the idea of exposing the stack depth to smart contracts, I’ve came up with a better idea to handle batching, and at the same time remove the stack limit without the downside of iterative gas metering. I’ll be publishing the new idea on the forum soon and I won’t be supporting this change, unless the other (better) idea is not accepted by the community.