In an attempt to clear up misc files from the root dir

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

  f871de00... build: make use of 76 lib/*.h renamed files
  ffd8e127... 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:

  c087374c... 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:

  13606bbf... build: make use of 93 lib/*.c renamed files
  5b6e7927... build: rename 93 lib/*.c files
  7d83dfff... build: commit 13606bbf 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

93 *.c source files renamed to use our standard naming scheme.

This change affects 77 files in libcurl's source tree.

Version number is removed in order to make this info consistent with
how we do it with other MS and Linux system libraries for which we don't
provide this info.

Identifier changed from 'WinSSPI' to 'schannel' given that this is the
actual provider of the SSL/TLS support. libcurl can still be built with
SSPI and without SCHANNEL support.

my_setopt and my_setopt_str no longer ignores curl_easy_setopt result.

Fixed some OOM handling issues.

my_setopt and my_setopt_str no longer ignores curl_easy_setopt result.

Fixed some OOM handling issues.

Overhauled FindWin32CACert()

Additionally function my_useragent() now provides default User-Agent string

Reviewing fields being free'd in free_config_fields() still pending

Additionally some code reorganization and direct OOM handling fixes,
just another step towards fixing curl tool issues uncovered 2011-09-15

Additionally fix data type of result vars for iconv() calls

Just a note about the fact that all VC[6/8/9/10] makefiles are generated
from the VC6 one as source.

Default libcurl's file names are kept equal to those used since Y2K.