default file transfer type is binary, not ascii;

default file transfer type is binary, not ascii;
commands which toggle settings can take an explicit on or off argument
to force the setting appropiately, show these arguments in usage;
synchronize synopsis and usage of commands; spacing; KNF;
other minor documentation tweaks.

written with help by jmc@

ok jmc@ (documentation), martynas@ (type usage and default file transfer type)