refactor: use vector of banks for algorithm I/O

[c-dilks]

• Algorithm Run method now operates on a BankVec, a std::vector of bank pointers
  • Run now returns void; instead it is allowed to mutate the input BankVec; this saves some time by avoiding copying banks
  • Start will set the index of the BankVec for each required bank, so Run avoids hashing (cf. previous design's BankMap, an unordered map of bank names to bank pointers, which requires extensive hashing)
  • Creator algorithms will need a pointer to the "new" bank in the input BankVec
• Algorithms may be initialized one of two ways:
  • call Start(): a default (algorithm-dependent) ordering of banks will be assumed by Run
  • call Start(std::unordered_map<std::string, int> m), where m provides the index of the BankVec for each bank

This design provides compatibility with @gavalian's idea of a BankStore:

struct BankStore {
  std::vector<hipo::bank> banks;                 // the vector of banks
  std::unordered_map<std::string, int> bankMap;  // bank name -> index in `banks` for that bank
}

If a user wants to use a BankStore, they would write the following (pseudocode):

Algorithm algo;
BankStore b = reader.getBanks(bank1, bank2);
algo.Start(b.bankMap);
while(event)
  algo.run(b.banks);

Alternatively, if a user wants to work with the banks and avoid the bank store, they need to know the order of the banks that the algorithm Run call expects (or change it using Start(map)):

Algorithm algo;
hipo::bank bank1, bank2;
algo.Start();
while(event) {
  bank1 = event.get("bank1");
  bank2 = event.get("bank2");
  algo.run({bank1, bank2});

This alternative, while slower, may be preferred in the case where refactoring one's analysis code to use BankStore is difficult.