Parse & InstructionHelper stuff

Changes (non-breaking):

• Converted the InstructionHelper class to partial (one part per region)
• InstructionHelper.FindCall and InstructionHelper.FindField methods now find any instruction that has a matching MethodInfo or FieldInfo operand regardless of opcode

Additions:

• InstructionHelper.FindCall and InstructionHelper.FindField methods with name-only overload + ignore case option (defaults to true)
• Parse.Item and Parse.Role overloads with includeNone option (defaults to false)
• ArraySegment<string> extensions for argument parsing: all methods in Parse.cs prefixed with Parse including an index parameter (defaults to 0)
  • ArraySegment counterpart of Int(string, out int result) is ParseInt(this ArraySegment<string>, out int result, int index)