Post PrettyTables.jl housekeeping

[bkamins]

@ronisbr - I open this issue to keep track of to-do related to PrettyTables.jl:

1. coverage of show.jl is quite poor now: https://codecov.io/gh/JuliaData/DataFrames.jl/tree/master/src/abstractdataframe; it would be great to add more tests at some point (this point should be reviewed after update manual and docstrings to PrettyTables.jl #2522 is merged as I did some clean up there)
2. add section in the manual on configuring PrettyTables.jl
3. add HTML and LaTeX backends

[ronisbr]

Good!

Just one question about 1: maybe I am mistaken, but the code snippets that are not tested seem to be related to the old printing mechanism, which are not used anymore. Am I wrong? The only line that is not tested in _show is the one that blocks floating point alignment if we have more than 200,000 cells.

[bkamins]

Am I wrong?

That is why I say that we should wait for #2522 as it removes them (and then probably it will be clean).

Still I think we do not have custom PrettyTalbles.jl kwarg tests (I assume that when manual entry is written it can be also used as additional tests).

[ronisbr]

Oh sorry, I am a bit lazy today 😊 Yes, we definitely should add tests with custom options of PrettyTables (at least the most common);

[bkamins]

PRs like #2542 show that it would be good to go back to this housekeeping issue at some moment (no rush - as probably everyone needs a break now 😄; I am updating tutorials).