tsvwrite writes non-compliant tsvs when a table is provided

[coxroy]

whenever a Matlab table is provided to tsvwrite, Matlab's builtin writetable is used to write the tsv. this can result in noncompliant tsvs if the user did not manually think to change empty/NaN/NaT/etc values to n/a.

possible solution is to call table2struct whenever a table is provided, with this struct then undergoing the already present checks for noncompliant values

[Remi-Gau]

Can reproduce the bug in dev and in master.
will push a hot fix in master.