68400d8b96 tests: Use explicit imports (practicalswift)
Pull request description:
Enable automatic detection of undefined names in Python tests scripts. Remove wildcard imports.
Wildcard imports make it unclear which names are present in the namespace, confusing both readers and many automated tools.
An additional benefit of not using wildcard imports in tests scripts is that readers of a test script then can infer the rough testing scope just by looking at the imports.
Before this commit:
```
$ contrib/devtools/lint-python.sh | head -10
./test/functional/feature_rbf.py:8:1: F403 'from test_framework.util import *' used; unable to detect undefined names
./test/functional/feature_rbf.py:9:1: F403 'from test_framework.script import *' used; unable to detect undefined names
./test/functional/feature_rbf.py:10:1: F403 'from test_framework.mininode import *' used; unable to detect undefined names
./test/functional/feature_rbf.py:15:12: F405 bytes_to_hex_str may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
./test/functional/feature_rbf.py:17:58: F405 CScript may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
./test/functional/feature_rbf.py:25:13: F405 COIN may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
./test/functional/feature_rbf.py:26:31: F405 satoshi_round may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
./test/functional/feature_rbf.py:26:60: F405 COIN may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
./test/functional/feature_rbf.py:30:41: F405 satoshi_round may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
./test/functional/feature_rbf.py:30:68: F405 COIN may be undefined, or defined from star imports: test_framework.mininode, test_framework.script, test_framework.util
$
```
After this commit:
```
$ contrib/devtools/lint-python.sh | head -10
$
```
Tree-SHA512: 3f826d39cffb6438388e5efcb20a9622ff8238247e882d68f7b38609877421b2a8e10e9229575f8eb6a8fa42dec4256986692e92922c86171f750a0e887438d9
fa5587fe71 qa: wait_for_verack by default (MarcoFalke)
Pull request description:
This removes the need to do so manually every time a connection is added.
Tree-SHA512: a46c92cb4df41e30778b42b9fd3dcbd8d2d82aa7503d1213cb1c1165034f648d8caee01c292e2d87d05b0f71696996eef5be8a753f35ab49e5f66b0e3bf29f21
fa87da2f172ae2e6dc15e9ed156a3564a8ecfbdd qa: Avoid start/stop of the network thread mid-test (MarcoFalke)
Pull request description:
This simplifies test writing by removing the need to handle the network thread in tests. E.g. start thread, join thread, restart thread mid-test, adding p2p connections at the "right" time, ...
Tree-SHA512: 533642f12fef5496f1933855edcdab1a7ed901d088d34911749cd0f9e044c8a6cb1f89985ac3a7f41a512943663e4e270a61978f6f072143ae050cd102d4eab8