Log Message:
Add a new -m option that prints sh script which invokes make for each
"interesting" package, where "interesting" is defined by the \ 
other
options given on the command line.

Rework the "rebuild", "delete", and "fetch" output \ 
modes to use a new
generic routine invoked with (the new) -m option.  Other new options
are:

 -a all packages (to make more packages becoming "interesting")
 -e adds an "existence check" to each of the lines of sh(1) style
    output (ala the current rebuild output)
 -r reverses the order in which the packages are listed
 -S package
    selects a subgraph of the installed package base
 -s print a simple list of packages instead of sh commands

Also: fix a dreadful bug in the group number assignment loop.  Groups
are now assigned more properly, meaning that wholely selected
subgraphs (via the new -S option) work.

Welcome to version 2.5.