etable - Shorter column width can cut off column names

[digikar99]

An example is here.

@rcoreilly suggested here that not using column-names in the column-width calculation helps maintain space-efficient consistent column-widths. But in cases like above, where the column-names aren't too long, a "show full headers" option can be helpful that when enabled takes the column-names-length for calculating column widths. Indeed, tooltips do work, but not having to depend on them for viewing the column names would be great!