Fix small actor conversion quirks

[kakaroto]

From @Talith on Discord :

So, many months ago I did an export of all the Monster manual from roll20 as a compendium, I have been (very slowly) working on fixing the actors. I have seen many people that have the same idea. My export was done with 8.9.* and decided to check the new one to see if the more prevalent errors were fixed. I know that its impossible to get a perfect conversion, but while fixing all the actors I think I can narrow the most prevalent errors (I don't know if they are easy to fix or even if they can be fixed)

1. Resistances and immunities: So I started noticing that several monsters had only grabbed piercing and bludgeoning resistance... missing slashing. After a new export I think I see the problem. It seems that it affects monsters with resistances that have a condition. The desc says: "Bludgeoning, piercing and slashing of nonmagical weapons" Bludgeoning and piercing were correctly assigned in Foundry, in my prev version the other text made slashing just not show. on this current version it adds a custom resistance. Many modules use the specific resistances for damage checks so it would be ideal to be able to get those properly marked. (Check a demilich as example)

2. Saving throws on many abilities: This is really easy to see on the Dragon breaths. I think the problem is that dragon breath DC's are actually derived from constitution (dragon's CON mod), but they require a DEX saving throw. So the description properly says a 18 DEX DC, but the roll itself will display a dex 13 DC (Check Adult black dragon as example).

3. Spell slots: I remember that back then I had to do a "find and replace" on ceraintext of the converted json (I opened actors.db) And through that managed to put the proper spell slots in the configuration. I don't remember exactly what I used as a find/replace but there was enough logic in the actors.db json to do it once per spell level and it would fix everything. (See Mage for an example)

All an all these are minor problems and it really affects more people that like me want to get the monster compendiums ready for drag n drop in foundry, but I just wanted to let you know about it because maybe some extra parsing in the descriptions could provide a not so difficult fix and just overall make the tool better.