Dealt with mixed use between (const char *) and (std::string) in a single join() call. Accompanying unit test.
Fixing style issues. Removing explicit inline statements.
Add overloads of an internal::append function to support mixed type strings::join(). There are special overloads for string ands const char * to maintain performance.
Added a test for mixed type strings::join().
Fixed style issues.
Merge branch 'variadic-join' into help-refactor
Simplify strings::join() invocation.