Better Visual Studio support

[SoftwareSamurai]

I would like to suggest two improvements to the Visual Studio support in PlatformIO.

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1. Support multiple boards in Visual Studio.

It could be as simple as modifying the CLI like this:
"platformio init --ide visualstudio --board teensy31 --board esp32dev"

Each board would generate a new project. The project files should be named according to the board it supports, not just "platformio.vcxproj / platformio.vcxproj.filters".
(Note that the ProjectGuid must be unique per project. It currently is not.)

All projects should then be placed into a single solution. (Currently the solution file is not automatically generated. It should be.) The solution file can be named "platformio.sln" - that's fine.

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2. Provide a way to update the project files without completely overwriting them.

Something like:
"platformio refresh --ide visualstudio --board teensy31 --board esp32dev"

When new libraries are installed, they must be added to the projects. This needs to be done without destroying the current project files. A developer may have made many changes unique to each project that need to be preserved. (Folders, files, settings, etc.)

[mikeym88]

Is this being actively worked on? If not, I'd be interested in working on this feature and submitting a pull request.