Monarch ID duplicates on tag change

[Andrei Gijgorev]

Edit: Okay, it's actually a bit more complicated than it seemed at first...

So what happens is that if a country changes tags from AAA to BBB via event, monarchs_aaa.txt is discarded and monarchs_bbb.txt is loaded instead, with a monarch from monarchs_bbb.txt immediately becoming the ruler. Now if AAA rises again as a new nation, monarchs_aaa.txt is loaded and a suitable monarch chosen as the ruler. So far, so good. However, the next monarch in monarchs_aaa.txt will rise to the throne in both countries, leading to duplicated IDs.

This bug can be circumvented by saving and reloading at any time after the tag change event and before the next monarch's startdate.

The behaviour can occasionally be observed in Watkabaoifbaaaaaa when Hongwu starts in 1368. It can also be manually reproduced in Watkabaoifbaaaaaa by doing the following:

1. In monarchs_chi.txt, change the startdate of Hongwu (ID 16137) to 'year = 1338'.
2. Start the 1337 scenario as 'Hands Off'.
3. Trigger event 7845962 for CHI (changes tag to MNG).
4. Trigger event 7845963 for MNG (creates CHI).
5. On 01/01/1338, Hongwu will be the ruler of both CHI and MNG.

Note that if step 4 is omitted and CHI doesn't exist, Hongwu will not rise to the throne in MNG.