Build functions and macros to manage comma-separated unique strings

Build these funcions and macros

 * GetStrsCommaUStr
   Get the number of strings of the comma-separated unique strings

 * AddStrCommaUStr
   Add a string to the comma-separated unique strings

 * AddCommaStrCommaUStr
   Add a comma-separated strings to the comma-separated unique strings

 * DelStrCommaUStr
   Delete a string from the comma-separated unique strings

 * FistStrCommaUStr
   Get the first string of the comma-separated unique strings

 * IsStrInCommaUStr
   Check whether a string is in the comma-separated unique strings

Note: comma-separated unique strings in case insensitive.

This commit closes #2026.