implement game configuration file

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

third-party/tomlc99/stdex/arrtab3.toml

@@ -0,0 +1,8 @@
+# INVALID TOML DOC
+[fruit.physical]  # subtable, but to which parent element should it belong?
+color = "red"
+shape = "round"
+
+[[fruit]]  # parser must throw an error upon discovering that "fruit" is
+           # an array rather than a table
+name = "apple"