Update indentation rules

[jsoo1]

1. Now something like the following will indent automatically so that people who want to adhere to 80 column lines can use the mode.

Mux(
    a=in,
    b=s0,
    sel=r0,
    out=out
);

2. Remove the CHIP regex and replace instead with the opening curly brace for a more general indentation rule.

3. Add a missing (previously undefined) variable - nand2tetris-1 so the indentation works when called.

4. Add initial value to cur-indented for reading clarity.

[CestDiego]

This looks pretty good. Thanks! :D

[jsoo1]

Thanks for the snappy merge 👍