Mop up cases of s/copy/take/, remove 'binding' terminology, whitespace police, and make obj/fn structural.

rustc: Use the passed-in tydescs for take and drop glue in parametric fns. Also fix a level-of-indirection problem with tydesc params.

rustc: Build tydescs for types, and make all take and drop operations go through the tydescs for simplicity (LLVM inlines them).

rustc: Move next_var_id back to the crate context in typechecking; we'll need it when collecting item types