This PR aims to spark the retirement of a questionable pattern I have found all over our code base. I will illustrate how this pattern encourages code duplication, lacks type safety, requires documentation and can be prone to bugs.
```
std::map<std::string, Object> mMap; // Stored in all lowercase for a case-insensitive lookup
std::string lowerKey = Misc::StringUtils::lowerCase(key);
mMap.emplace(lowerKey, object);
std::string lowerKey = Misc::StringUtils::lowerCase(key);
mMap.find(lowerKey);
mMap.find(key); // Not found. Oops!
```
An alternative approach produces no such issues.
```
std::unordered_map<std::string, Object, Misc::StringUtils::CiHash, Misc::StringUtils::CiEqual> mMap;
mMap.emplace(key, object);
mMap.find(key);
```
Of course, such an alternative will work for a `map` as well, but an `unordered_map` is generally preferable over a `map` with these changes because we have moved `lowerCase` into the comparison operator.
In this PR I have refactored `Animation::mNodeMap` accordingly. I have reviewed and adapted all direct and indirect usage of `Animation::mNodeMap` to ensure we do not change behaviour with this PR.
Swimming-related fixes
See merge request OpenMW/openmw!247
(cherry picked from commit 8be328ef80f29e9692e29d24beefa8ced16537a7)
738c71fd Extend the "turn to movement direction" mode for swimming up and down.
10d3e82b New setting "swim upward coef"
Container is only used to add elements, iterate over all of them and
clear. Multimap adds overhead for all of these operations without any
benefits. Reduce Animation::resetActiveGroups CPU time usage by 50%.
Use a set to check for group start existence.
Reduce time taken from 2.6% to 0.08% and
MWMechanics::MechanicsManager::update from 7% to 5%
in relative CPU time usage for a scene with ~100 actors.
The pointer to the LightListCallback is now stored in the Animation, which eliminates the need for dynamic_cast. Also, when the object root is recreated, the previously used LightListCallback will be reused, so we no longer need the objectRootReset() notifier.
Finally, there was a bug when saving and reloading the game, the getIgnoredLightSources() were not being set, as the ActorAnimation constructor completes before the NpcAnimation sets the ObjectRoot. This was solved by creating the LightListCallback in advance in the Animation constructor.
