- generic f() to retrieve identities from a list of pubkeys

- Implements equality and add time attribute to Transaction class

…because InputSource __eq__() wasn’t implemented
- store pending sources into InputSource

- Rename f() to wot_lookup()

- Remove no longer used constant

- #135: remove get_uid_from_pubkey()
 Replace two uppers function with identity_of() which requests
/wot/identity-of/<pubkey/uid> and only returns members identities with
their pubkey and uid, which improves performances.
- change is_member() as a wrapper of identity_of()
- change usage in `id`, `cert`, `tx`, `net`, `blocks`

- #189: Handle in a good way wot/identity-of requests exceptions

- #206: Set a sleep for async requests: `blocks` and `net` for leaves

- 2) Rename `best_node()` to `best_endpoint_address()`
- 3) argos: print https link in case of port 443
- 4) Use CurrencySymbol singleton
- 6) Remove useless comment
- 11) Term clarification: chart −> table

- Black formating on the file

in order to play with intermediaries tx