Manage the storage information process

[federicozanardo]

Reference #5 and #12.
It is necessary to manage carefully the storing process in the commitment layer. The SVM pushes, in a particular stack (only the push operation is allowed), all the information that must be stored in the commitment layer. The "execution"* phase (not the virtual machine), when the SVM completed the execution and returned a positive result, must wait to store the information before carrying on the state of the contract.

* For "execution" phase I mean the phase that precedes and follows the execution of the bytecode by the SVM. Tasks performed in this phase are loading the program for the SVM and checking if there is information to store in the commitment layer.

| Other stuff                                                                                             |
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| "Execution" phase (i.e. loadProgram, checkLastInstructionIsHalt, ...)  |
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| SVM execution                                                                                      |
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| "Execution" phase (i.e. store information in the commitment layer, ...) |
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| (Maybe other stuff?)                                                                              |