On many systems, python refers to Python 3.

Fixes bbolli#87

Fixes bbolli#179

Certain options should never be negative, and a count of zero should
actually download zero posts, not all of them. Also, make sure we can
read cookiefile before we back up any blogs.

Included revisions:
- Add check for confusing -i -n 0

Posts are now read from disk each time they are needed, instead of
keeping them all in memory.

This is especially needed when --save-notes is used with a large blog,
as this often results in many gigabytes worth of HTML that does not fit
into free memory all at once.

qsize() acquires a mutex on the queue, which is shared between threads.
Read it only once to avoid a race condition.

Included revisions:
- Make typing optional

Included revisions:
- Saner non-option arguments

Included revisions:
- Remove log_queue, better status and account logic
- Better tracking and synchronization on ThreadPool.queue.qsize
- Remove remaining_posts
- Remove getting_tup
- Put back the account parameter

Fixes bbolli#169

Fixes #1

Fixes bbolli#202

Behaves similar to cp -u or or rsync when copying local files into the
media directory.

Included revisions:
- Use prev_archive for style.css

Store the original exception instead of trying to reconstruct it later.
The reference cycle can be avoided with traceback.clear_frames.

Closes #12

- required dependencies are now assumed instead of using hacky fallbacks
- optional dependencies are now listed in pyproject.toml

This is a python 2 thing.

Fixes #15