Branching factor constructor parameter

[sharwell]

Currently the branchingFactor parameter specified in several constructors in this library poses a potential problem for users attempting to drop-in replace existing collections with the ones defined here. For example, consider the following:

var list = new List<int>(capacity);
list.AddRange(source);

If this code is converted to TreeList<T> using a find and replace operation, you get this:

var list = new TreeList<int>(capacity);
list.AddRange(source);

This code compiles and executes correctly when capacity is greater than 2, but the internal APIs (and performance) are potentially negatively impacted and maintainability is hurt since capacity is not what the argument is used for.

A solution should be provided which helps people migrate from standard .NET collections to these collections without hitting these problems.