use `vroom::col_big_integer()` for integers to avoid overflow?

[khusmann]

I notice in #16 you switched from col_integer() to col_double() to avoid integer overflow.

readr doesn't support big integers, but vroom does via vroom::col_big_integer(): https://vroom.r-lib.org/articles/vroom.html#column-types

We may want to try out col_big_integer() out instead of col_double(); it appears to work with the gps data you posted in #16, at least.