Merged in iprt++ dev branch.
header (C) fixes
*: spelling fixes, thanks Timeless!
Automated rebranding to Oracle copyright/license strings via filemuncher
*: s/RT_\(BEGIN|END\)_DECLS/RT_C_DECLS_\1/g
iprt/*: __BEGIN_DECLS -> RT_BEGIN_DECLS; __END_DECLS -> RT_END_DECLS.
RTBase64Encode* testcase and adjustments.
RTBase64: The decoding part (untested).