With this PR we refactor a `premultiplied alpha` user string set by `characterpreview.cpp` into a more flexible mechanism allowing us to assign any state to GUI textures. We can consider these changes more future proof than the previous approach.
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.
To construct serializer from given entities:
* Data source/destination - any value that has to be serialized/deserialized,
usually already existing type.
* Format - functional object to define high level serialization logic to
define specific format and data schema. Like order of fields, allocation.
* Visitor - functional object to define low level serialization logic to
operator on given data part.
* BinaryWriter - copies given value into provided buffer.
* BinaryReader - copies value into given destination from provided buffer.
* SizeAccumulator - calculates required buffer size for given data.
