Respect MANPATH and/or -M switch

[GSI]

I keep man pages of other (usually remote) systems on my local machine and would like to read (and search!) them using mangl without having to type the path to the path on the file system.

From man manpage for quick reference:

-M path
           Override the list of directories to search for manual pages.  The
           supplied path must be a colon (‘:’) separated list of
           directories.  This option also overrides the environment variable
           MANPATH and any directories specified in the man.conf(5) file.

 MANPATH   Override the standard search path which is either specified in
           man.conf(5) or the default path.  The format of MANPATH is a
           colon (‘:’) separated list of directories.  Invalid directories
           are ignored.  Overridden by -M, ignored if -l is specified.

           If MANPATH begins with a colon, it is appended to the standard
           path; if it ends with a colon, it is prepended to the standard
           path; or if it contains two adjacent colons, the standard path
           is inserted between the colons.