maintain and is only going to get worse as more are used. So instead, add a new
uint64_t member to cmd_entry which is a bitmask of upper and lowercase options
accepted by the command.
This means new single character options can be used without the need to add it
explicitly to the list.
- move the code back into cmd.c and merge with the existing functions where
possible;
- accept "-tttyp0" as well as "-t/dev/ttyp0" for clients;
- when looking up session names, try an exact match first, and if that fails
look for it as an fnmatch pattern and then as the start of a name - if more
that one session matches an error is given; so if there is one session called
"mysession", -tmysession, -tmysess, -tmysess* are equivalent but if there
is also "mysession2", the last two are errors;
- similarly for windows, if the argument is not a valid index or exact window
name match, try it against the window names as an fnmatch pattern and a
prefix.