Update StringExtensions class (#115)
Update StringExtensions class (#115)

Convert StringExtensions to Internal class instead of public - prevent outside packages seeing this extension method if declared using Robosharp namespace
If public is still preferred, added appropriate xml summary tags.

Co-authored-by: RFBomb <b6da3e7e946a609842ee18bc149be4668ee6a316@gmail.com>
tjscience/RoboSharp,tjscience/RoboSharp