Jump labels stored. Added some reminder TODOs

src/MOS6502.js

         if (tokens[0] === 'define'){
           // Variable label!!
         } else if (tokens[0][tokens[0].length - 1] === ':'){
-          // Jump label!!
+          // Jump labels!
+          // TODO: Finish me!!
+          let lbl = tokens[0].substr(0, tokens[0].length - 1);
+          if (lbl in this.__jmplabels)
+            throw new Error("Jump label '" + lbl + "' defined more than once at program address " + toHexString(this.__PC));
+          if (lbl in this.__varlabels)
+            throw new Error("Jump label '" + lbl + "' matches already existing variable name at program address " + toHexString(this.__PC)); 
+          this.__jmplabels[lbl] = this.__PC;
         } else if (tokens[0].length === 3){
 
           let StoreSingleOp = (code)=>{
           };
 
           let StoreBranchOp = (code) => {
+            // TODO: If value is not valid, test to see if it's a jump or variable value.
             if (tokens.length === 2){
               if (token[1][0] === '$' && (tokens[1].length === 3 || tokens[1].length === 5)){
                 let v = parseInt(token[1].substr(1), 16);
               procFailed = StoreSingleOp(0xC8); break;
 // --- JMP
             case 'jmp':
+              // TODO: Update value results to test for jump names if value not a number.
               if (tokens.length === 2){
                 if (tokens[1].startsWith("$") && tokens[1].length === 5){
                   let v = parseInt(tokens[1].substr(1), 16);
               break;
 // --- JSR
             case 'jsr':
+              // TODO: Update value results to test for jump names if value not a number.
               if (tokens.length === 2){
                 if (tokens[1].startsWith("$") && tokens[1].length === 5){
                   let v = parseInt(tokens[1].substr(1), 16);