remove vestigial prolog/ directory (#444)

src/mod.rs

@@ -0,0 +1,27 @@
+extern crate dirs;
+extern crate ordered_float;
+extern crate prolog_parser;
+#[cfg(feature = "rug")]
+extern crate rug;
+#[cfg(feature = "num-rug-adapter")]
+extern crate num_rug_adapter as rug;
+
+#[macro_use]
+mod macros;
+mod clause_types;
+pub mod instructions;
+#[macro_use]
+mod allocator;
+mod arithmetic;
+mod codegen;
+mod debray_allocator;
+mod fixtures;
+mod forms;
+mod heap_iter;
+pub mod heap_print;
+mod indexing;
+mod iterators;
+pub mod machine;
+pub mod read;
+mod targets;
+pub mod write;