Overhaul of the table render

Footnote handling still needs to be done
Exponents are now aligned
Fix to when scientific notation is selected
Fixes to rendering of exponentials
Fix to zeros not being rendered in tables
Tables now fold correctly

(Table folding is where multiple columns are combined into one through
interleaving)
Added rudimentary footnote support
Added footnote symbol alignment
Merge pull request #31 from jasp-stats/table-renderer-overhaul

Table renderer overhaul
Fixes to table cell padding
Tweaks to Correlation
Tweaks to significant figures in descriptives
Tweaks to dp in independent samples t-test