Initial support of rake scaffolding task on Windows platform.
The task requires privilege to create symlink via mklink command.
Avoid hardcoding the D3D9 library dependencies.
This change should actually be part of this commit 971fa90c1091668e1daca2c9d77f21596b338a5f.
Enhance Urho3D.pc file generation to support MSVC and MinGW better.
Simplify the pkg-config invocation example for MinGW cross-compiler since the Urho3D library name is already corrected. No need to sed anymore.
For Travis CI - switch CI build to use OS X build environment.