fix help message for Func and BoolFunc flags #430

* have '.Type()' for boolfuncValue return "boolfunc" (dedicated value,
  which now makes it distinct from funcValue)
* hide extra "(default )" by stating that "" should be treated as
  a zero value for a boolFlag
  note:
  - a boolfuncValue matches 'case boolFlag:', as it
    implements the boolFlag interface,
  - treating "" as a value which shouldn't trigger a "(default )"
    for a regular Bool flag does not look like a breaking change
* hide extra "[=something]" for boolfuncValue
* set default placeholder name for "boolfunc" and "func" flag types

0 files changed, 0 insertions, 0 deletions