Add a reader for other formats supported by pandas

[timvink]

Currently, we are missing:

• read_sas
• read_feather
• read_html
• read_xml
• read_hdf
• read_orc
• read_parquet
• read_sas
• read_spss
• read_stata

We could add them, but we would need to add an option where you can specify which readers you want to enable, because each one will require a regex to run on all your markdown content (which can slow down your build times).

[timvink]

We now have the option to specify/modify the list of readers, so it's easier to add these additional readers.