Improve support for groups of transactions

[montyly]

Most of the Algorand system relies on multiple contracts that interact with each other within a group of transactions, while currently tealer analyse one contract at the time. This leads to miss a lot of context-related information, and prevents the development of more complex analyses.

We should make tealer work on a set of contracts, and adds the semantics related information. Detecting the group of transaction, and what function should be called within the group might be tricky. I think we can try to have a couple of heuristics to detect this automatically, and have has a fallback mechanism a user configuration.

Plan:

• Add support for a group of transactions
• Add group configuration by the user
• Detection of functions that should be called within a group
• Creation of a “group information” printer
• Update the existing detectors to rely on the group information