PortableBuildTools

• Fixed #32
• Fixed install message error not preventing installation

Changed msvc version detection according to mmozeiko

• Added bodge for nvcc support
• Fixed download speed not being as high as it should be
• Fixed scaling on Windows 7, 8.1, and old versions of Windows 10
• PortableBuildTools is now single-instanced, to prevent other instances from interfering with one another

improved console argument handling (for the last time trust)

Fixes #30