Project edits for pr517

[vir-mir]

• Modification in tests
• Removing old style file examples
• Removing old style (yield from) in docs
• Rename psycopg2 to psycopg2-binary in docs
• added note in docs about going to python3.5.2+
• Interim fix due to issues Fix python support 3.8.0 #533
• refactor docs style
• aded the example code

@asvetlov @jettify since the changes are not compatible with previous versions, I propose to upgrade to major version 1.0.0

[codecov]

Codecov Report

Merging #534 into master will increase coverage by 0.25%.
The diff coverage is 93%.

@@            Coverage Diff            @@
##           master    #534      +/-   ##
=========================================
+ Coverage   94.35%   94.6%   +0.25%     
=========================================
  Files          27      27              
  Lines        3740    3728      -12     
  Branches      171     169       -2     
=========================================
- Hits         3529    3527       -2     
+ Misses        179     164      -15     
- Partials       32      37       +5

Impacted Files	Coverage Δ
tests/test_async_transaction.py	100% <ø> (ø)
aiopg/log.py	100% <ø> (ø)	⬆️
tests/test_sa_priority_name.py	100% <ø> (ø)
tests/test_sa_engine.py	98.92% <100%> (ø)	⬆️
aiopg/pool.py	100% <100%> (ø)	⬆️
tests/test_sa_transaction.py	86.59% <100%> (ø)	⬆️
tests/test_connection.py	98.63% <100%> (ø)	⬆️
tests/test_sa_distil.py	100% <100%> (ø)	⬆️
tests/test_async_await.py	100% <100%> (ø)
tests/test_pool.py	100% <100%> (+0.24%)	⬆️
... and 10 more

---

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[gjcarneiro]

In the next release notes, besides saying it requires async/await, there should probably be a note about dropping of the deprecated non-asynchronous iterator protocol (__iter__). Now only __aiter__ is available.

So this works:

async for row in cursor: ...

This used to work, but was already deprecated, and no longer works:

for row in cursor: ...

There was already a deprecation warning: https://github.com/aio-libs/aiopg/blob/v0.16.0/aiopg/cursor.py#L384-L387

[vir-mir]

@gjcarneiro thx, this is a good point!

[vir-mir]

@popravich if you review at this PR, I would be grateful

[vir-mir]

@asvetlov @popravich You are noted in the documentation support here https://readthedocs.org/projects/aiopg/

The question is, are the hooks configured to build the master and the tags? I watch the last build was a long time ago. https://readthedocs.org/projects/aiopg/builds/

[asvetlov]

Thanks for the PR.
What is your account on readthedocs?
I want to add you as the project admin

[webknjaz]

Reviewing this is PITA. Maybe you could split it into atomic chunks?

[lgtm-com]

This pull request introduces 3 alerts when merging a72f3ac into 82f3ced - view on LGTM.com

new alerts:

• 3 for Unreachable code

[vir-mir]

in master