Define environments in which transactions are considered

In order to find bottlenecks in the system, it makes sense to:

• Replace different parts of the system with dummy implementations that are almost instantaneous in order to minimize their contribution to the processing time. Candidates for this are: p2p layer, network, mempool, etc.
• Lift constraints such as gas estimation and block size.
• Consider the baker in a network with just one node/baker or in a larger network.
• Tweak compilation options such as GC.

Also, figure out what is the easiest environment/setup to implement as a starting point for the benchmarking app.