Moved prototypes to nsock_proxy.h
Removed 'data_' prefixes to encoding/decoding functions to avoid confusion with functions that deal with proxy internal data structures.
Return 1 on success to (try to) improve consistency.
Added skeletton for having px_info list in each Nsock IOD.

When establishing the tunnel through proxy chain, we need to track status of
each proxy (storing R/W buffers, stats, retries...).

This patch lets proxies store and manage whatever structure they want to have
for this in a Nsock IOD. Since types can differ between proxy types, the
proxy_info are stored as a list of void *, ordered like the proxy nodes.
Removed the proxy-specific tcp_connect hook.

This simplifies the interface that proxies export to the library but also relies
upon the assumption that a proxy chain starts with a TCP connection from the
scanner to the next hop proxy. That will be enough ATM.
Use an intermediate proxy_chain pointer for readability.
Implemented a more robust URI parser. Code largely adapted from ncat/http.c.
Removed per-node information structures as well as data encoding/decoding
interface.

These were unused and I think won't be required by any proxy type (HTTP and
SOCKS).
Removed unused http_proxy_info structure.
Replaced a couple macros by corresponding static inline functions.
Removed unused PROXY_CTX_NODES() macro.
Added a new NSE_STATUS_PROXYERROR status type to report proxy-related errors
back to caller.
Added handling of the new NSE_STATUS_PROXYERROR case.
Default port is set to -1 (and not zero) when not specified in proxy specification string.
Added support to resolve proxy hostnames.
Removed list of todo items from source.
Added svn properties.
Let NSE use nsock proxy chains.
Let FPEngine use nsock proxy chains.
Let our DNS resolver use nsock proxy chains.
Enfore node=NULL on error.