Adds basic support for class functions and methods. (#1057)

* adding methods to the ast

* pre commit stuff?

* implementation of class functions

* implemented methods

* some cleanup

* more cleanup

* add newlines in test programs

* pre-commit fixups

* added include of return_term.h

* a test of a method calling another method

* replacing Member with Declaration

* removing the member.h etc files

* clarify a type annotation

* update uses of FunctionDeclaration

* remove ReturnTarget, no longer needed

* more cleanup

* more cleanup

* yet more cleanup, playing with pre-commit

* did a pre-commit run --all-files

* fixed const issue

* remove comment

* checking dependencies in BUILD files and headers

* pre-commit working now

* refactor NominalClassType to just hold a pointer to the class declaration

* remove Member from rtti

* responding to Geoffreys review

* change field_types to a non-member function

executable_semantics/interpreter/exec_program.cpp

@@ -22,7 +22,6 @@ void ExecProgram(Nonnull<Arena*> arena, AST ast, bool trace) {
     for (const auto decl : ast.declarations) {
       llvm::outs() << *decl;
     }
-    llvm::outs() << "********** type checking **********\n";
   }
   SourceLocation source_loc("<Main()>", 0);
   ast.main_call = arena->New<CallExpression>(
@@ -30,8 +29,17 @@ void ExecProgram(Nonnull<Arena*> arena, AST ast, bool trace) {
       arena->New<TupleLiteral>(source_loc));
   // Although name resolution is currently done once, generic programming
   // (particularly templates) may require more passes.
+  if (trace) {
+    llvm::outs() << "********** resolving names **********\n";
+  }
   ResolveNames(ast);
+  if (trace) {
+    llvm::outs() << "********** resolving control flow **********\n";
+  }
   ResolveControlFlow(ast);
+  if (trace) {
+    llvm::outs() << "********** type checking **********\n";
+  }
   TypeChecker(arena, trace).TypeCheck(ast);
   if (trace) {
     llvm::outs() << "\n";