fix: Child process termination, workspaces, gitignore, logger

* Now using cargo workspaces, means you can `cargo run` from toplevel.
* Command execution now is cwd independent.
+ Added pretty_env_logger which lets us leverage log crate for easy
  logging.
* Windows now uses the win32job crate to ensure that all child processes
  will properly terminate when the parent process does.
+ Added empty rustfmt.toml to ensure everyone uses default rustfmt
  settings.
* Gitignore now ignores more stuff.

.gitignore

@@ -1,6 +1,6 @@
 # See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
 
-# dependencies
+# JS/TS dependencies
 /node_modules
 /.pnp
 .pnp.js
@@ -8,8 +8,9 @@
 # testing
 /coverage
 
-# production
+# Build artifacts
 /build
+/target
 
 # misc
 .DS_Store
@@ -22,5 +23,4 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
-
-*.log
+*.log