Added functions for detecting known folders per-platform. Not tested on Windows yet, but who cares?

source/mijin/virtual_filesystem/filesystem.cpp

@@ -1,6 +1,8 @@
 
 #include "./filesystem.hpp"
 
+#include "../platform/folders.hpp"
+
 namespace mijin
 {
 
@@ -37,7 +39,7 @@ std::vector<fs::path> OSFileSystemAdapter::getRoots()
 
 fs::path OSFileSystemAdapter::getHomeFolder()
 {
-    return "/home/mewin"; // very TODO
+    return getKnownFolder(KnownFolder::USER_HOME);
 }
 
 std::vector<FileInfo> OSFileSystemAdapter::listFiles(const fs::path& folder)