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

1 files changed, 84 insertions, 0 deletions

diff --git a/lib/pop3.h b/lib/pop3.h
new file mode 100644
index 000000000..1b6859955
--- /dev/null
+++ b/lib/pop3.h
@@ -0,0 +1,84 @@
+#ifndef HEADER_CURL_POP3_H
+#define HEADER_CURL_POP3_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 2009 - 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
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+/****************************************************************************
+ * POP3 unique setup
+ ***************************************************************************/
+typedef enum {
+  POP3_STOP,         /* do nothing state, stops the state machine */
+  POP3_SERVERGREET,  /* waiting for the initial greeting immediately after
+                        a connect */
+  POP3_STARTTLS,
+  POP3_CAPA,
+  POP3_AUTH_PLAIN,
+  POP3_AUTH_LOGIN,
+  POP3_AUTH_LOGIN_PASSWD,
+  POP3_AUTH_CRAMMD5,
+  POP3_AUTH_DIGESTMD5,
+  POP3_AUTH_DIGESTMD5_RESP,
+  POP3_AUTH_NTLM,
+  POP3_AUTH_NTLM_TYPE2MSG,
+  POP3_AUTH,
+  POP3_APOP,
+  POP3_USER,
+  POP3_PASS,
+  POP3_COMMAND,
+  POP3_QUIT,
+  POP3_LAST          /* never used */
+} pop3state;
+
+/* pop3_conn is used for struct connection-oriented data in the connectdata
+   struct */
+struct pop3_conn {
+  struct pingpong pp;
+  char *mailbox;          /* Message ID */
+  char *custom;           /* Custom Request */
+  size_t eob;             /* Number of bytes of the EOB (End Of Body) that
+                             have been received so far */
+  size_t strip;           /* Number of bytes from the start to ignore as
+                             non-body */
+  unsigned int authtypes; /* Supported authentication types */
+  unsigned int authmechs; /* Accepted SASL authentication mechanisms */
+  unsigned int authused;  /* SASL auth mechanism used for the connection */
+  char *apoptimestamp;    /* APOP timestamp from the server greeting */
+  pop3state state;        /* Always use pop3.c:state() to change state! */
+};
+
+extern const struct Curl_handler Curl_handler_pop3;
+extern const struct Curl_handler Curl_handler_pop3s;
+
+/* Authentication type flags */
+#define POP3_TYPE_CLEARTEXT 0x0001
+#define POP3_TYPE_APOP      0x0002
+#define POP3_TYPE_SASL      0x0004
+
+/* This is the 5-bytes End-Of-Body marker for POP3 */
+#define POP3_EOB "\x0d\x0a\x2e\x0d\x0a"
+#define POP3_EOB_LEN 5
+
+/* This function scans the body after the end-of-body and writes everything
+ * until the end is found */
+CURLcode Curl_pop3_write(struct connectdata *conn, char *str, size_t nread);
+
+#endif /* HEADER_CURL_POP3_H */