Add pandas .dropna equivalent

[Gabriel-p]

There is apparently no easy way to drop rows with masked values (as explained in https://stackoverflow.com/q/50256012/1391441).

A dropna equivalent should be added.

[pllim]

For now... maybe this?

>>> df = t.to_pandas()
>>> df.dropna()
>>> t2 = Table.from_pandas(df)

[Gabriel-p]

Yes, but that forces me to have pandas installed. I want my code to depend on the smallest number of packages possible.

[moon05]

@pllim Hi! Are you taking care of this? I was just curious if pretty much having a function with what literally one of the SO answers are stating would work? Since functools and itertools are already imported in ascii that seems like the easiest way to go? Or are there other things to be wary of here? I was thinking of giving this a go, but wanted to make sure that what I am thinking is in right path.

[bsipocz]

@moon05 - I'm sure @pllim is not working actively on this, you're most welcome to open a PR with a prototype solution and get the discussion going in there.

[moon05]

@bsipocz thanks! I will open a PR tonight hopefully.