Block, Script, ScriptInterpreter: capitalize deps for new libcoin names

Gets them compiling again.

Block.js

@@ -7,7 +7,7 @@ function spec(b) {
   var Bignum = b.Bignum || require('bignum');
   var Put = b.Put || require('bufferput');
   var Step = b.Step || require('step');
-  var Transaction = b.Transaction || require('./transaction').class();
+  var Transaction = b.Transaction || require('./Transaction').class();
   var TransactionIn = Transaction.In;
   var TransactionOut = Transaction.Out;
   var COINBASE_OP = Transaction.COINBASE_OP;

Script.js

@@ -4,7 +4,7 @@ function spec(b) {
   var config = b.config || require('./config');
   var log = b.log || require('./util/log')(config);
 
-  var Opcode = require('./opcode').class();
+  var Opcode = require('./Opcode').class();
 
   // Make opcodes available as pseudo-constants
   for (var i in Opcode.map) {

ScriptInterpreter.js

@@ -4,7 +4,7 @@ function spec(b) {
   var config = b.config || require('./config');
   var log = b.log || require('./util/log')(config);
 
-  var Opcode = require('./opcode').class();
+  var Opcode = require('./Opcode').class();
 
   // Make opcodes available as pseudo-constants
   for (var i in Opcode.map) {
@@ -13,7 +13,7 @@ function spec(b) {
 
   var bignum = b.bignum || require('bignum');
   var Util = b.Util || require('./util/util');
-  var Script = require('./script').class();
+  var Script = require('./Script').class();
 
   function ScriptInterpreter() {
     this.stack = [];