You don't have to use Visual Studio, I just recommend it because it's easiest for newcomers. People who have another preferred way to code can use that, you just need to set up meson as the compile command.

Currently only MSVC is supported by our build script on Windows, but MinGW support is planned. Note that these are compilers (which are, sadly, not platform-agnostic), while your question seems to concern IDEs (which usually are). Support for specific IDEs is severely lacking due to our decision to use a high-level build system called Meson (with a low-level build system called Ninja, unless you use VS's own) instead of each individual build system that comes with each individual IDE, which makes it possible to compile TPT without an IDE. As long as your IDE supports external build systems though, it should be possible to set them up to interact with Ninja. Atom should definitely be able to do this relatively easily, although I'm unclear on the details.

To answer your question, no, in fact, not even compiling "in Visual Studio" is supported in the usual sense, for if you tell Meson to generate a VS solution, your experience won't be as comfortable as you might expect from VS because you'd be using it for something that it isn't made for (despite Microsoft's claims). The recommended way to compile TPT on Windows is through your command line of choice. Currently this has to support execution of .bat files in order to set up the environment required by MSVC, because this is the only supported compiler on Windows. How you make your changes to the source is beyond the scope of this recommendation though. I just use whatever text editor I have on hand.