Changes after writing C# source gen

[ousnius]

Here's part of the changes I needed to do after writing a C# / .NET Source Generator that uses the nif.xml due to C#'s stronger type checking.

In this PR I only included changes that shouldn't cause any compatibility issues and don't leave much room for discussion.

Changes:

• INF# was renamed to #FLT_INF# because C# has different infinities depending on the type (float/double).

• VER# and #USER# were placed in #BSSTREAMHEADER# where appropriate.

• New Vector4-specific default values were created, because Vector3 default values were used for Vector4.
• Token global had cond added to its attrs and operator had calc added to its attrs.
• Minor token placement in places where previously the string was used.
• 0/1 to true/false for bool field defaults.
• Addition of != 0 for bitwise conditions to make it forced to a bool rather than a number.
• Typo fix: "Begining" -> "Beginning"