This makes such natural commands as "MKD ~user/newdir" or "STOR ~/newfile"
do what they are supposed to instead of failing miserably with the
"File not found" error.
This involves a bit of code reorganization. Namely, the code doing
glob(3) expansion has been separated to a function; a new function
has been introduced to do tilde expansion; the latter function is
invoked on a pathname before the former one. Thus behaviour mimicing
that of the Bourne shell has been achieved.