Get rid of unnecessary cast
Expand Span comment
Add ability to create lexer from io.Reader
Add support for _ in integer literals
Up the go version to 1.14
Mention new integer literal support in README
Add binary, octal, and hexadecimal literal support
Add rune support

We UTF-8 now boy
Adjust how spans are printed
Add support for if/else/return/true/false
Add support for -*/!<>
Add token spans to README
Initial lexer finished
Actually don't include the code

You learn by typing
Initial inclusion of chapter 1 code
Initial commit