overhaul: add support for stock splits and automated awv reporting

[stadlmax]

• support for stock splits
• support for automated AWV reporting
• use decimal.Decimal for a more robust handling of floating point numbers
• round sales proceeds as Schwab seems to do so for sub-cent values
• introduce new format for transactions, separating RSUs and ESPPs to e.g. allow automated reporting for AWV purposes or to allow a more generic treatment of currency conversions

[szotsaki]

I checked the before-after comparison and they were equal. So far I couldn't check the foreign currency tab because of the account fill-up workaround

[szotsaki]

Just one more round of automatic checks :)

[szotsaki]

#10 passes all tests now, let's get everything ready to merge! :)

[stadlmax]

Great news, would you mind going over the conversations to see if there is still a comment not addressed? I'll do the same :)

[szotsaki]

I made some bugfixes and additions in my branch. They start at commit "Make "Anlage SO - Fremdwährungen" summary more precise".

Could you please look at them? After the fixes I think we can merge the two PRs.

[szotsaki]

Newest version of YFinance is messy as it can be...

They removed session support, so you should remove it. However, they're adding it back in ranaroussi/yfinance#2505.

Then there are various other issues scattered around, like ranaroussi/yfinance#2474 which prevents stock splits retrieval, so this part of code wouldn't work anyhow.

It also complains about unset proxies, but it's just a warning: ranaroussi/yfinance#2512

I'll continue later.

[szotsaki]

Fixed some minor issues on my side and adjusted better to the changed code.

Apart from these comments, I don't find anything else currently. I think the temporarily missing session handling can be solved by just removing the session parameter and as soon as it's back in YFinance, we can add it back here, too.

Everything else can be part of usual bug reports from wider audience :)

[stadlmax]

yfinance issues seems like a show-stopper for unfortunately

[stadlmax]

@szotsaki likely not nicely or over-engineered, but i revisited the historical prices through YF again

• now with a manual and human-readable cache (i.e. in case YF breaks in the future again, it would be possible to potentially share or manually update some csv files)
• tested things with more recent releases of YF (0.2.62/0.2.63) and things seem to work again

[szotsaki]

Thank you for the changes. I rebased #10, re-run the generator, and it worked the same as before :).

Let's merge!

(Ps. please merge my PR with the commit structure kept)