This fixes several issues with compatibility with C++20. C++23 was also
tested, but apparently it does not have any additional breaking changes
compared to C++20 (or we don't have those).
VCMI still uses C++17 as before - goal is only to make potential
transition easier.
There were 2 cases that are deprecated in C++20 that we use:
- Floating point operations on enums are deprecated
- `this` can no longer be captured when using default capture by value
`[=]`
Both of those should now be replaced with code that works fine in both C+
+17 and in C++20 mode
Nullkiller AI will now prefer giving its scout heroes faster units to
optimize their movement points on next turns.
Unit selection logic:
- AI prefers to give 'weak' units that won't affect army strength of main
hero. Unit is considered 'weak' if its level below 4 or if its AI value
is below 1% of total army strength. So AI can give high-tier unit to
scout, but only if main hero already has massive army.
- Within weak units, if hero is moving on terrain with penalty, AI will
always prefer units that are native to this terrain. So on snow AI will
always prefer unit from Tower even if its speed is lower than unit from
another faction.
- Within remaining candidates, AI will prefer unit that will give higher
movement points limit. This also means that in case of H3 rules, all
units with 11+ speed will be viewed as equally good
- If there are multiple units with same speed, AI will prefer unit with
lowest AI value
AI will no longer leave the defense of a threatened town in order to bring the army to another hero.
AI will no longer send heroes to die outside of towns that already have a garrisioning hero inside, if there's a stronger enemy hero lurking around the town.
AI no longer rushes towns that don't have a citadel or better when there is a scary enemy hero around.
AI will no longer try to maximize defenses by using the strongest possible defender. Instead it will try to use the most appropriate defender. The most appropriate is considered to have roughly 75% power of the threat and the score will be lower but still above zero the bigger the deviation is.
