If FILENAME is omitted, the printname of FEATURE is used as the file name,
and `load' will try to load this name appended with the suffix `.elc' or
`.el', in that order. The name without appended suffix will not be used.
+If your system supports it, `.el.gz' files will also be considered.
If the optional third argument NOERROR is non-nil,
then return nil if the file is not found instead of signaling an error.
Normally the return value is FEATURE.