Some TR events are not handled

[RealCLanger]

Description of the bug
In my TR history there are a few events that don't seem to be picked up correctly by pytr yet and hence are missing in account_transactions.csv after dl_docs.

These are namely:
OUTGOING_TRANSFER (Probably an old name for outgoing bank transfer events)
benefits_spare_change_execution (Transactions for the Spare Change plan)
ssp_tax_correction_invoice: Tax corrections, e.g. after different trades with negative saldo occur on the same day.

To Reproduce
Steps to reproduce the behavior:

1. Run the command pytr dl_docs for an account that has either of the events mentioned above
2. According entries will be missing in account_transactions.csv

Expected behavior
Matching csv entries should be written.

Environment

• OS: Windows
• pytr version: 0.2.5

[Katzmann1983]

Merged. Thanks for the commit and keeping the code simple and clean