* Fix TextCanvas `CanvasError("Attribute extends beyond text...")

* `[[]] * ...` causes
  list of 1 list with pointers
  amount equal to multiplier
  instead of "list of lists"
* Add 2 basic font tests which check for Canvas create issue
* Add few type annotations during debug process

Fix: #554

* Force tests to restore default encoding in tearDown

Tests order change should not cause tests failures

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

Fix #552

Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

* Revert "Allow to pass parameters when open pop_up (#480)"

This reverts commit 55b6a920
Fix #480

* Update gitignore: reverted PR contained MacOS specific files not intended to present in repo

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

* Return original code to the deprecated getters and setters

* Make more aggressive deprecation warning

Fix: #548

* Return original code to the deprecated getters and setters

* Make more aggressive deprecation warning

Fix: #548

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

* Fix incorrect type cast in vterm (`apply_mapping` should return `bytes`)

Add `time.sleep(0.1)` to the event loop tests:
  in the worst scenario on windows and slow machine
  function in parallel thread/async can wait up to 80 milliseconds (tested)
Add type annotations to the `vterm` and `test_vterm` to simplify error lookup.
* Fix `DeprecationWarning` in doctests & examples
* Add `pytest` configuration in `pyproject.toml` without migration
* `Signals.emit()` rework: stop `user_args` join with `weak_args`

Partial: #544
Partial: #512
Partial: #406

* drop `sleep`: not enough effective with pytest

* set timer for errors raise to 0: faster raise, faster test done

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

* Fix text layout for `align="center", wrap="clip"`

- Fix: Prevent zero run length in text layout.

Refs: urwid#542

* Add test for "clip" text layout fix

Refs: #542

* [BREAKING CHANGE] Fix: #90 Remove idle emulation from asyncio event loop

Re-implement abandoned PR #418
* Fix "not hashable `AttrSpec`" and it's instance creation price (use `__slots__`)
  `AttrSpec` instances may be created in huge amount,
  with slots this process consume less resources.
* `Terminal` is always created with event loop,
  if not provided -> `SelectEventLoop` is used
* Fixed `TornadoEventLoop` & `AsyncioEventLoop` logic
  (Tornado IOLoop is asyncio based)

For extra details see original PR.

* Make `AttrSpec` immutable and hash-reusable

* Update IDLE callback comment

* Update urwid/display_common.py

Co-authored-by: Ian Ward <ian@excess.org>

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>
Co-authored-by: Ian Ward <ian@excess.org>

* Add type annotations and optimize `urwid.font`

* optimize `separate_glyphs`: do not mutate `gl`, less temporary variables
* add `__repr__` and human-friendly exception reraise on render
* add type annotations to satisfy mypy

Partial: #406

* Add FontRegistry metaclass and use self-registration for fonts.

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>

* Deprecate `__super` hack

`super()` should be called explicit

* Update urwid/util.py

Co-authored-by: Ian Ward <ian@excess.org>

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>
Co-authored-by: Ian Ward <ian@excess.org>

* [BREAKING CHANGE] Refactoring: Split event loop in several modules

* `urwid.main_loop` is split into multiple modules which is easier to maintain
* `urwid.compat` is not used anymore and removed
* `TornadoEventLoop`, `GLibEventLoop`, `TwistedEventLoop` and `TrioEventLoop`
  accessible ONLY if required dependencies installed
  (like: Tornado installed -> `TornadoEventLoop` is accessible for import)
* `TornadoEventLoop` use the same idle logic as `AsyncioLoop`:
  tornado.ioloop.IOLoop is asyncio based.
* Trio < 0.15 is not supported. Version 0.15 was released almost 3 years ago.
* Tornado < 5.0 is not supported. Tornado 5.0 was released 5 years ago.

* Remove useless shebang

* `EventLoop` should be real abstract
* add new module docstrings

* Fix docstrings

* remove unneeded import

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Co-authored-by: Aleksei Stepanov <alekseis@nvidia.com>