Rebase V4 onto current master (2dee9daf)

[michaelosthege]

Restores mergeability of v4 w.r.t. master.

I resolved merge conflicts by prioritizing the changes from the v4 branch.

On every commit I ran the following script to replace aet occurences:

import pathlib
import textwrap

extensions = [".py", ".rst"]
replacements = [
    ("import aesara.tensor as aet", "import aesara.tensor as at"),
    ("aet.", "at."),
]

def process_file(fp: pathlib.Path):
    with open(fp, encoding="utf8") as file:
        lines = file.readlines()

    newlines = []
    for l, line in enumerate(lines):
        newline = line
        for old, new in replacements:
            newline = newline.replace(old, new)
            if newline != line:
                print(textwrap.dedent(f"""
                L{l} in {fp}
                → {line.strip()}
                → {newline.strip()}
                """))
        newlines.append(newline)

    with open(fp, "w", encoding="utf8") as file:
        file.writelines(newlines)
    return


def run():
    for ext in extensions:
        for file in pathlib.Path(r"E:\Source\Repos\pymc3").glob(f"**/*{ext}"):
            try:
                process_file(file)
            except:
                print(file)
                raise
    pass

if __name__ == "__main__":
    run()