c-generic/libpubnub: First preliminary version of generic C library, work in progress
c-generic/libpubnub pubnub_subscribe_http_cb(): Fix user callback call
c-generic/libpubnub: Proper handling of channel information in case of multiple messages received
c-generic/libpubnub: Proper curl error handling all over the map

This includes some slight semantics tweaks, also in pubnub-sync, and enhanced error reporting in the example demo.
c-generic/libpubnub: Rename callbacks to a consistent scheme

pubnub_http_input_cb() -> pubnub_http_inputcb(), pubnub_timeout_cb() -> pubnub_event_timeoutcb()
c-generic/libpubnub: Proper timeout handling

New pubnub_callbacks.timeout() call instead of .wait() parameters.
c-generic/libpubnub: Send the mandatory HTTP headers (V, User-Agent)
pubnub_sync_wait(): Fix timeout cb being unable to set new timeout
c-generic/libpubnub: Add support for secret key and infrastructure for cipher key

We link to libcrypto to acquire the MD5 hashing routine.
c-generic/libpubnub: Move the signing to crypto.c:pubnub_signature()
c-generic/libpubnub: Make all debug prints really go to stderr
c-generic/libpubnub: Add support for AES256 encryption when cipher_key is set
c-generic/libpubnub: Add gitignore for generated files
c-generic/libpubnub pubnub_sync_done(): Avoid leaking sync->{response,channels} using newly factored out pubnub_sync_reset()
c-generic/libpubnub pubnub-sync.c: Include pubnub-sync.h for better consistency guarantee
c-generic/libpubnub: Make sure pubnub_connection_cleanup() is called before pubnub_connection_finished()

This allows finished_cb to issue another PubNub request, making it possible to easily callback-chain requests.
c-generic/libpubnub: Add libevent support as an alternative for the sync backend.
c-generic/libpubnub Makefile: Drop -DDEBUG by default; use make XCFLAGS=-DDEBUG to get debug version
c-generic/libpubnub Makefile: Split essential CUSTOM_CFLAGS to SYS_CFLAGS
c-generic/libpubnub pubnub_callbacks.unused: Extra item for forward binary compatibility