Added the "omit errors" capability to join_thingy.

Works!
table1_latex_thingy now uses the omit_errorbars kwarg for Spitzer.

I may turn this into a on/off switch with a kwarg.
Now join_columns_whatever uses "%.*f" instead of round() to round strings.

it's much better because you keep trailing zeros and everything lines up nice <3

Also I updated the tests to reflect this new usage.