Fix observed crash when shutting down services server where the client_t
protocol was pointing to a freed service's protocol description string.

This was the last pointer in client_t and should resolve the last race
conditions (memory ownership issues) with its data members.

This also resolves a small memory leak in getnodeclient() where the last
client "gotten" would have its heap-duplicated protocol string leaked.

This fixes issue #495.

is actually an authenticated local user (when usernum != 0).

msg_client_hfields() no longer saves the client->user as the SMB SENDERUSERID
hfield when the client hasn't been authenticated (as is the case with normal
SMTP). The SENDUSERIDs were redundant and misleading for unauthenticated
SMTP-received mail messages, so that's now fixed.

bcc32 pads differently than msvc when an odd-sized string is inserted in
the middle of a structure, so chagne the addr[] field to a nice "power of 2"
size: 128. This allows sbbsctrl.exe client window to work again.
Use uint16_t instead of WORD for the TCP port element, just because.

New Features:
- Multiple bindings for each service
  Use comma-separated interfaces on Interface= lines in the ini file.
  Default is now "0.0.0.0,::"
- IPv6 support
- TLS support for the webserver and (non-static) services
  New TLS option in services.ini (ie: Options=TLS)
- Decrease LEN_SCAN_CMD to 35 chars, increase the CID field to 45 chars,
  and rename the MAIL_CMD string to IPADDR.  I think this frees up the
  note field for SysOp use.

all exported functions and data types using a 32-bit time_t (time32_t).

by properly const-ifying the appropriate functions and variables.

Not yet tested on Win32