A ton of style change to wallet.cpp
Summary:
- Remove blanket std import from wallet.cpp
- Add braces around control flow statements
- Remove useless scopes.
- Use nullptr instead of NULL
- Various other small changes.
Test Plan:
make check ../qa/pull-tester/rpc-tests.py
Reviewers: freetrader, sickpig, kyuupichan, awemany, #bitcoin_abc
Reviewed By: freetrader, #bitcoin_abc
Differential Revision: https://reviews.bitcoinabc.org/D301