Replaced strbuf_reset and strbuf_clear by STRBUF::clear; strbuf_clear wasn't necessary anymore for initializing STRBUF from STATIC_STRBUF, because of use of constructor
Moved __strbuf_expandbuf to STRBUF::reserve; also removed alloc_failed since it never actually gets set to anything but zero
Moved strbuf_puts to STRBUF::append/operator+=
Replaced strbuf_putc with STRBUF::push_back