initial structure + nix build (#1)

(incl. cross-compiling)

.gitignore

@@ -2,10 +2,7 @@
 # will have compiled files and executables
 debug/
 target/
-
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
-Cargo.lock
+result/**
 
 # These are backup files generated by rustfmt
 **/*.rs.bk
@@ -18,4 +15,6 @@ Cargo.lock
 #  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
-#.idea/
+#.idea/
+#
+.direnv