Add more readers to the LispReader

Next up:
* [ ] Char reader: `#\x`
* [ ] More numbers:
   * [ ] hexadecimal: `#x`
   * [ ] octal: `#o`
   * [ ] binary: `#b`
   * [ ] any base: `#nr` (e.g., `#36r`)
   * [ ] rational: `123/32`
   * scientific notation:
      * [ ] `123E-3` -> `0.123`
      * [ ] `0.123e20` -> `1.23e+19`
      * [ ] `123d23` -> `1.23d+25`
   * [ ] alternate complex notation: `#c(2 1)`