Add .gitignore with binaries and some folders

This commit adds a .gitignore file which includes a few common
binary file extensions, dumps, the build-script's working folder,
a private folder for convenience and an ignore for the VSCode
editor's configuration folder.

.gitignore

@@ -8,6 +8,8 @@
 *.o
 *.so
 
+*.dump
+
 # Full ignored folders
 *.build/
 *.private/