build: Added Visual Studio 2010 (VC10) project files

Carrying on from commit 11025613b9 added VC10 project files which are
capable of supporting side-by-side compilation, 32-bit and 64-bit
builds as well as support for some of the third-party libraries curl
uses.

Makefile.am

@@ -44,6 +44,9 @@ VCPROJECTS = projects/README projects/Windows/VC8/lib/libcurl.sln	    \
  projects/Windows/VC9/curl.sln	\
  projects/Windows/VC9/lib/libcurl.sln projects/Windows/VC9/lib/libcurl.tmpl	\
  projects/Windows/VC9/src/curlsrc.sln projects/Windows/VC9/src/curlsrc.tmpl
+ projects/Windows/VC10/curl.sln	\
+ projects/Windows/VC10/lib/libcurl.sln projects/Windows/VC10/lib/libcurl.tmpl	\
+ projects/Windows/VC10/src/curlsrc.sln projects/Windows/VC10/src/curlsrc.tmpl
 
 VC_DIST = \
  vs/t/README \