`ciCompareLen(a, b, b.size()) == 0` expression is an equivalent of checking for
equality of `a` prefix with size `b.size()` with `b`.
`ciCompareLen(a, b, a.size()) == 0` is also the same thing but `a` is a prefix
`b` should start with.
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.
OSG 3.4 adds the ability to place Drawables directly in the scene graph, without a Geode decorating them. Leveraging this should give a small performance boost, because the redundant Geodes increase culling overhead.
There is still an oustanding issue with the RemoveDrawableVisitor no longer working correctly, because Drawables can have multiple parents.
