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, 11 insertions, 11 deletions

diff --git a/lib/curlx.h b/lib/curlx.h
index 42c62958d..9dc90a004 100644
--- a/lib/curlx.h
+++ b/lib/curlx.h
@@ -34,29 +34,29 @@
    functions while they still are offered publicly. They will be made library-
    private one day */
 
-#include "curl_strequal.h"
-/* "curl_strequal.h" provides the strequal protos */
+#include "strequal.h"
+/* "strequal.h" provides the strequal protos */
 
-#include "curl_strtoofft.h"
-/* "curl_strtoofft.h" provides this function: curlx_strtoofft(), returns a
+#include "strtoofft.h"
+/* "strtoofft.h" provides this function: curlx_strtoofft(), returns a
    curl_off_t number from a given string.
 */
 
-#include "curl_timeval.h"
+#include "timeval.h"
 /*
-  "curl_timeval.h" sets up a 'struct timeval' even for platforms that
-   otherwise don't have one and has protos for these functions:
+  "timeval.h" sets up a 'struct timeval' even for platforms that otherwise
+  don't have one and has protos for these functions:
 
   curlx_tvnow()
   curlx_tvdiff()
   curlx_tvdiff_secs()
 */
 
-#include "curl_nonblock.h"
-/* "curl_nonblock.h" provides curlx_nonblock() */
+#include "nonblock.h"
+/* "nonblock.h" provides curlx_nonblock() */
 
-#include "curl_warnless.h"
-/* "curl_warnless.h" provides functions:
+#include "warnless.h"
+/* "warnless.h" provides functions:
 
   curlx_ultous()
   curlx_ultouc()