Adding Pod::Man as a dependency
[lib] using `Pod::Man` instead of relying on `perldoc` being installed
[lib] replacing Pod::Man with Pod::Text

Pod::Text doesn't need to be passed to nroff in order to produce
human-readable output.  The reason why we want to use a module instead of
`perldoc` is that `perldoc` isn't always installed on all machines and all
distributiions and thus it's possible to have unnecessary breakages.
Version bump 0.5.5 -> 0.6.5