Closes #854

After squashing most of our compiler warnings, up'ed the default
warning level from 3 to 4 in order to increase the likelyhood of
catching future warnings.

Updated the makefiles and Visual Studio project files to support moving
the authentication code to the new lib/vauth directory that was started
in commit 0d04e859e1.

find . -name .gitignore -print0 | xargs -i -0 sort -o '{}' '{}'

Prior to this change some Release configurations had an active
configuration assignment to their Debug counterpart.

In addition to commit 709cf76f6b, removed the USE_SSLEAY preprocessor
variable from the Visual Studio project files as it isn't required
anymore.

Visual Studio 2005 and above defaults to disabling the startup banner
for the Compiler, Linker and MIDL tools (with /NOLOGO). As such there
is no need to explicitly set the SuppressStartupBanner directive, as
this is a leftover from the VC7 and VC7.1 projects being upgraded to
VC8 and above.

Defined the DEBUGBUILD pre-processor variable to allow extra logging,
which is particularly useful in debug builds, as we use this and Visual
Studio typically uses _DEBUG.

We could define DEBUBBUILD, in curl_setup.h, when _MSC_VER and _DEBUG is
defined but that would also affect the makefile based builds which we
probably don't want to do.

As this pre-processor definition is defined in curl_setup.h there is no
need to include it in the Visual Studio project files.