Added a missing space.
Fixed trim_sstring() not checking for the first char when searching from the end.
Added a special return value for when there is nothing to trim for trim_sstring().
Added a missing assigment to NO_ERROR_SS in split_sstring().
Added checks for when the string is empty in split_sstring(s)().
Redone and corrected the decumentation.

Before this it was a mess and it was hard to read and find what you were looking for in the tons of information everywhere that was badly structured and hardly readable, not to mention there was a lot of overlap with functions of the same type that could be easily fixed.