Don't mangle arguments containing spaces and other special characters,
pass them unchanged to the proxy or server as applicable.
More robust parsing of server parameters: don't hit on partial words;
use ssl_server2's default values.
Minor style improvements.
This commit introduces the script `programs/test/udp_proxy_wrapper.sh` which can
be used to wrap the SSL server binary `programs/ssl/ssl_server2` by the UDP
proxy application `programs/test/udp_proxy` while maintaining the same
interface from the command line.
Specifically, given UDP proxy arguments ARGS_UDP and SSL server arguments
ARGS_SSL, the command line
> ./udp_proxy_wrapper.sh ARGS_UDP -- ARGS_SSL
behaves like
> ./ssl_server2 ARGS_SSL
wrapped by
> ./udp_proxy ARGS_UDP
The motivation and benefit of this is that scripts like `ssl-opt.sh` can be used
with the server command line `P_SRV` modified to `./udp_proxy_wrapper.sh
ARGS_UDP -- DEFAULT_ARGS_SSL` which will result in all tests being executed for
an SSL server behind a UDP proxy.
