Added error reporting and fixed some minor bugs in the tokenizer.
Revert "Added error reporting and fixed some minor bugs in the tokenizer."

This reverts commit e77320584ce0cffa9a5b88f4b1d5e78d5006b118.
Revert "Revert "Added error reporting and fixed some minor bugs in the tokenizer.""

This reverts commit 3f3a655520e2c76ca1bf3ce4f4a8e9c0d2dab5a9.
Began fleshing out some test cases in a lisp file. Implemented nice
printing of lists and pairs.