implement game configuration file

this integrates https://github.com/cktan/tomlc99 into the repo as a dependency

third-party/tomlc99/stdex/keys09.toml

@@ -0,0 +1,8 @@
+# THE FOLLOWING IS INVALID
+
+# This defines the value of fruit.apple to be an integer.
+fruit.apple = 1
+
+# But then this treats fruit.apple like it's a table.
+# You can't turn an integer into a table.
+fruit.apple.smooth = true