D3648: show: Get rid of extraneous space if `tip` also has other bookmarks

[Yuya Nishihara]

> -names_tags = '{if(names % "{ifeq(name, 'tip', '', name)}", " ({label('log.{colorname}', join(names % "{ifeq(name, 'tip', '', name)}", ' '))})")}'
> +names_tags = '{if(names % "{ifeq(name, 'tip', '', name)}", " ({label('log.{colorname}', separate(names % "{ifeq(name, 'tip', '', name)}", ' '))})")}'

`separate()` can't be used here since it takes non-list arguments.

`separate(sep, arg1, arg2, ...)`

What we can do for now is to move the separator to the inner loop, and
strip the leading/trailing separator.

`strip(names % "{ifeq(..., "{name} ")}")`

Maybe we'll need a function to filter out empty values?