Revert changes relative to lib/*.[ch] recent renaming

This reverts renaming and usage of lib/*.h header files done
28-12-2012, reverting 2 commits:

  f871de0... build: make use of 76 lib/*.h renamed files
  ffd8e12... build: rename 76 lib/*.h files

This also reverts removal of redundant include guard (redundant thanks
to changes in above commits) done 2-12-2013, reverting 1 commit:

  c087374... curl_setup.h: remove redundant include guard

This also reverts renaming and usage of lib/*.c source files done
3-12-2013, reverting 3 commits:

  13606bb... build: make use of 93 lib/*.c renamed files
  5b6e792... build: rename 93 lib/*.c files
  7d83dff... build: commit 13606bbfde follow-up 1

Start of related discussion thread:

  http://curl.haxx.se/mail/lib-2013-01/0012.html

Asking for confirmation on pushing this revertion commit:

  http://curl.haxx.se/mail/lib-2013-01/0048.html

Confirmation summary:

  http://curl.haxx.se/mail/lib-2013-01/0079.html

NOTICE: The list of 2 files that have been modified by other
intermixed commits, while renamed, and also by at least one
of the 6 commits this one reverts follows below. These 2 files
will exhibit a hole in history unless git's '--follow' option
is used when viewing logs.

  lib/curl_imap.h
  lib/curl_smtp.h

lib/curl_darwinssl.c

@@ -6,7 +6,7 @@
  *                             \___|\___/|_| \_\_____|
  *
  * Copyright (C) 2012, Nick Zitzmann, <nickzman@gmail.com>.
- * Copyright (C) 2012 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -23,11 +23,10 @@
 
 /*
  * Source file for all iOS and Mac OS X SecureTransport-specific code for the
- * TLS/SSL layer. No code but curl_sslgen.c should ever call or use these
- * functions.
+ * TLS/SSL layer. No code but sslgen.c should ever call or use these functions.
  */
 
-#include "curl_setup.h"
+#include "setup.h"
 
 #ifdef USE_DARWINSSL
 
@@ -43,12 +42,12 @@
 #include <sys/sysctl.h>
 #endif
 
-#include "curl_urldata.h"
-#include "curl_sendf.h"
-#include "curl_inet_pton.h"
-#include "curl_connect.h"
-#include "curl_select.h"
-#include "curl_sslgen.h"
+#include "urldata.h"
+#include "sendf.h"
+#include "inet_pton.h"
+#include "connect.h"
+#include "select.h"
+#include "sslgen.h"
 #include "curl_darwinssl.h"
 
 #define _MPRINTF_REPLACE /* use our functions only */
@@ -56,7 +55,7 @@
 
 #include "curl_memory.h"
 /* The last #include file should be: */
-#include "curl_memdebug.h"
+#include "memdebug.h"
 
 /* From MacTypes.h (which we can't include because it isn't present in iOS: */
 #define ioErr -36