Refactor the folder structure which only had 2 'real' modules, now it's more real, no need for splitting into folders beside the external one

src/basic_os.h

@@ -0,0 +1,49 @@
+#pragma once
+
+struct FileIter {
+    bool   is_valid;
+    bool   is_directory;
+    String absolute_path;
+    String relative_path;
+    String filename;
+
+    String    path;
+    Allocator allocator;
+    union {
+        struct Win32_FileIter *w32;
+        void                  *dir;
+    };
+};
+
+String   ReadFile(Allocator arena, String path);
+bool     WriteFile(String path, String data);
+String   GetAbsolutePath(Allocator arena, String relative);
+bool     IsValid(const FileIter &it);
+void     Advance(FileIter *it);
+FileIter IterateFiles(Allocator allocator, String path);
+void     InitOS(void (*error_proc)(const char *, ...));
+
+bool DeleteFile(String path);
+String  GetExePath(Allocator allocator);
+String  GetExeDir(Allocator allocator);
+bool    FileExists(String path);
+bool    IsDir(String path);
+bool    IsFile(String path);
+String  GetWorkingDir(Allocator arena);
+bool    IsAbsolute(String path);
+int64_t GetFileModTime(String file);
+String  WriteTempFile(Allocator allocator, String data);
+
+
+
+
+double GetTimeMicros(void);
+
+enum MakeDirResult {
+    MakeDirResult_Success,
+    MakeDirResult_Exists,
+    MakeDirResult_NotFound,
+    MakeDirResult_ErrorOther,
+};
+
+MakeDirResult MakeDir(String path);