Reduce shell invocations by chaining commands together.
Use 'echo' instead of 'printf \\n'.
Use 'read -s' instead of 'stty [-]echo', because we don't have 'stty'
in old msysgit.
Use 'bash' instead of 'sh' as 'read -s' is bash-specific (in case we
ever switch to dash or some other POSIX-only shell).
Signed-off-by: Karsten Blees <blees@dcon.de>