Save GlideN64 Shaders to Bizhawk folder instead of Mupen64Plus folder

Currently the Shader files generated by the GlideN64 plugin are stored in the following location which makes it hard to find them when the Shaders become corrupt, corruption of these files causes the GlideN64 plugin in Bizhawk to display wrong colours/corrupt graphics.

%AppData%\mupen64plus\shaders

You need to be able to easily delete the Shaders in situations where they become corrupted or incompatible due to a change of video card or drivers. Storing them in a location that is neither named after the emulator nor the video plugin, is unintuitive. It'd also be nice if they were stored in the Emulator's installation folder somewhere (if they can be moved out of AppData).