Added a null and bool test. Also wrote a test script.

I wrote a script that will run a file with ts and compare the output with the expected output given in the comments of the file it ran (identified by using //>). If you give it a directory, it runs itself on each file or directory in that directory. So far it only prints what files it failed on and doesn't support multi-line expected results but I think it'll still be useful.

Example:
test.ts:
```
print 42; //>42
```
Then run:
```
./checkResults test.ts
```