* Copy recipient code structure from Sosthene00 fork
* Move SilentPayment struct to receiving
* Provide shared_secret as input argument for scan_for_outputs
Also refactors a number of things to enable this change: calculate A_sum
and outpoints_hash in the test code instead of the library, remove the
obsolete hash_outpoints function from the library move calculate_P_n
and calculate_t_n to utils.rs.
* Add debug trait implementation for Label
* Refactoring
* Add get_receiving_address function for getting sp-address per label
* Refactor scan_for_outputs and rename to scan_transaction
* Provide tweak data to scan_transaction function
* Expand README.me
* Remove all references to input.rs from other files
* Move test vector test to integration test folder
* Move test vector file into integration test folder
* Move input.rs to tests folder