Implement Windows support

Introduce solution file and dependencies to be able to create
PHP extension for MS Windows operating system. For this binding
you need to have libvirt-0.dll and its dependencies on system
path or PHP binary path.

Signed-off-by: Michal Novotny <mignov@gmail.com>
Windows sources: Fix header file typo

Signed-off-by: Michal Novotny <mignov@gmail.com>
Increment version number to 0.5.0

Signed-off-by: Michal Novotny <mignov@gmail.com>