more care around generated names, fixes #60 #82 and #97

test/codegen/expect/constructors.js

 var constructors;
 (function(exports) {
   'use strict';
   class A extends core.Object {
   }
   class B extends core.Object {
     B() {
     }
   }
   class C extends core.Object {
@@ skipping 24 matching lines @@
       super.E(name);
     }
   }
   class G extends core.Object {
     G(p1) {
       if (p1 === void 0)
         p1 = null;
     }
   }
   class H extends core.Object {
-    H(opt$) {
-      let p1 = opt$ && 'p1' in opt$ ? opt$.p1 : null;
+    H(opts) {
+      let p1 = opts && 'p1' in opts ? opts.p1 : null;
     }
   }
   class I extends core.Object {
     I() {
       this.name = 'default';
     }
     I$named(name) {
       this.name = name;
     }
   }
@@ skipping 54 matching lines @@
   exports.G = G;
   exports.H = H;
   exports.I = I;
   exports.J = J;
   exports.K = K;
   exports.L = L;
   exports.M = M;
   exports.N = N;
   exports.P = P;
 })(constructors || (constructors = {}));