[Groff] recursive subdirectory search in GROFF_TMAC_PATH

[Dorai Sitaram]

Wouldn't it be useful to have the possibility of recursively searching the 
subdirectories of a directory in GROFF_TMAC_PATH, typically with the addition 
of a double-slash at the end of the concerned directory's name? (Cf. TeX's 
TEXINPUTS.)
E.g.,
export GROFF_TMAC_PATH=$HOME/groffinputs//:
would cause .mso to search for its file at any subdirectory depth under 
$HOME/groffinputs.
--d