Imagehelper

This was going to be 0.4.5, but a new kwarg was added to the localfile logger which may be backwards incompatible
* moved tests and test-data
* cleaned up Python exceptions
* cleaned up docstrings
* added new `errors.ImageError_InstructionsError`
* added some tests, specifically for localfile and s3 "simple saving"
* localfile saving now logs the "filepath" (new kwarg to logger)
* adopted black formatting

* python3 support
* the way commandline optimization libraries are called/setup has drastically changed. instead of multiple variables being used to control this, they are now in a single `OPTIMIZE_SUPPORT`. they are also autodetected. this ensures we do not run programs that do not exist on an operating system.
* added tests to ensure the resizer doesn't have null objects

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mypy support
drop py2.7 for mypy
renamed some s3 functions for parity with superclass:
imagehelper.saver.s3.SaverManagerFactory.saver_manager -> SaverManagerFactory.manager
imagehelper.saver.s3.SaverManagerFactory.saver_simple_access -> SaverManagerFactory.simple_access

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This release replaces boto with boto3. This library upgrade required renaming
several public and private items. In order to simplify code and ease upgrading,
using the old names will cause Exceptions to be raised. Py2 support is
maintained for users with legacy projects.

* switched to boto3
* renames:
* `._s3Connection` -> `._s3_client`
* `.s3_connection` -> `.s3_client`
* `bucket_public_headers` -> `boto3_ExtraArgs_default_public`
* `bucket_archive_headers` -> `boto3_ExtraArgs_default_archive`

Please note the former "*_headers" configurations now use the boto3 arguments
for `ExtraArgs`.
For example:

- bucket_public_headers={
- "x-amz-acl": "public-read"
- "Cache-Control": "max-age=5184000",
- }

is now:

+ boto3_ExtraArgs_default_public={
+ "ACL": "public-read",
+ "CacheControl": "max-age=5184000",
+ }

The `boto3_ExtraArgs_*` configurations are passed directly to boto3 as `ExtraArgs`

* imagehelper.saver.s3 now has `NonCloseableBufferedReader()` a helper class to get around a boto3 bug. see source, tests and demo for more information.

* Dealing with files/filelike objects was an "elegant hack" under Python2. With Python2+Python3 side-by-side support it became messy. Thanks to a workaround needed for a bug in the botocore/s3 transfer library, this was standardized to use `io.xxx` classes and is much cleaner.

2021.04.07
* improved imports
* Python2 now recognizes `io.IOBase`

2021.03.25
* packaging layout