Optimize ps termlet. Runs in ~1.3sec instead of ~2sec on an AMD E-350.

I prefer variable names that can be immediately understood without deciphering abbreviations. How about `first_line` instead, with the initial value being `true`?

Also, that being said, can't the two `if` blocks actually be **_merged_** to create a much more concise and elegant termlet? Currently, we're checking whether we are in the header line in two different places using two different methods.