StringSegment wishlist

[Tratcher]

I tried to use StringSegment to parse headers and found that half of the string methods I was using are not available.

• Implicit converter from string (but not to string)
• .Empty, .None (null)
• Indexer
• .Subsegment(int offset) - right now it only has Subsegment(int offset, int length)
• .IsNullOrEmpty(StringSegment value)
• StringSegment.Equals(string, StringSegment, StringComparison)
• .Split(char[])
• StringBuilder.Append(StringSegment) & InlineStringBuilder.Append(StringSegment)
• .GetHashCode(StringComparer.OrdinalIgnoreCase)
• .GetHashCode() (that doesn't substring)

More to come...