* Introduced the `Option<A>` type to represent values that might not be there.
  * Replaced values representing failure (like `-1`) with `Option` to indicate the possibility of failure.

* Replaced possibly-invalid types with `Option`s. Now if you if have an instance - it's guaranteed to be valid.

* Replaced magic values (like using positive integers for managed object indexes and negative integers for static object indexes) with proper semantic types to help with code clarity.

* Replaced dangerous numeric casts that could under/overflow with typesafe alternatives (`PInt` positive 32bit integer type) that guarantee no such things can happen.

* Replaced instances of `List` which were being used as stacks with `Stack`.

* Replaced as many fields in objects as possible with readonly ones to indicate that we have no intent of changing them after the object is constructed. This is a part of 'objects should stay valid after construction' philosophy.

* Added logging for potentially dangerous operations (like int -> uint).

* Replaced primitive loop guards with cycle tracking that tracks seen objects. This eliminates the false positives and errors out sooner if we actually have an error.

* Replaced places where things got cancelled silently with emitting warnings / errors. Failures should never be silent.

* Fixed algorithm that checks if a type contains reference types: it didn't account for nested value-types which eventually have reference types in them and only looked for reference types in the first level.

* Fixed bad lookups in `PackedCoreTypes`. Also made `PackedCoreTypes` to be fully initialized, without any missing entries.

* Added a warning about the inability to crawl the `[ThreadStatic]` variables.

* Improved search speed by:
  * caching search results.
  * downcasing everything before the search and then using fast ordinal string comparisons instead of slower `OrdinalIgnoreCase` comparisons.

* Improved documentation by adding new docstrings and converting existing docstrings into proper XMLDocs. Now IDEs and tools can properly render the documentation.

* Rewrote a part of code using C# 7.3 (supported since Unity 2019) to enhance readability.

* bumped version to 4.1.2

* Added capability to copy the root path as text in "Find GC roots" window.

* Added information about source fields that are pointing to the object in "Find GC roots" window.

* Added progress reporting to Unity when a memory snapshot is being converted from the Unity format to our format.

The old data files contain fields serialized with `-1` offsets. We know these are invalid and should be skipped during reading.

…ng read for non-array types.

Now instead of having `bool isArray` and `PInt arrayRank` we have one field `Option<PInt> arrayRank` which makes sure we are not capable of representing the illegal state.

…ed namespaces yet.

Fix for Unity 2022.2

Tested with Unity 2019.4.40f1.

From arturaz - Refactor and fix