improve configure on windows

[SAM-tak]

Summary of changes

• Add "FindWindowsSDK" module

• If found WindowsSDK, use it to DXSDK path

• Add CMake Variable for support XInput

• Add OIS_ prefix to all option variable of CMake

Affected backeds

• CMake
• Windows
• DirectInput
• XInput

[Ybalrid]

Hey, many thanks for this! I'm going to test if everything is alright (seems good at a glance) on my side and merge this. This would also solve the issue #42

[Ybalrid]

Fix #42