v0.8.0 2016-05-23 La Forclaz (VS)

• Build depend on topkg.
• Relicense from BSD3 to ISC.
• Tweak Fmt.Dump.option to indent like in sources.
• Add Fmt.Dump.signal formatter for Sys signal numbers.
• Add Fmt[.Dump].result, formatter for result values.
• Add Fmt.{words,paragraphs} formatters on US-ASCII strings.
• Add Fmt.exn[_backtrace]. Thanks to Edwin Török for suggesting.
• Add Fmt.quote.
• Rename Fmt.text_range to Fmt.text_loc and simplify output when range is a position.