Extend annot-tsv, adding several new options

[pd3]

-d, --delim .. add support for other delimiters, not just tab

-h, --headers .. allow header lines in different formats. This is motivated by the common use of files with the first row containing column names but without the leading # character.

-I, --no-header-idx .. suppress column index numbers in the printed header. When given twice, drops the entire header

--help .. changed from -h, --help to just --help. Note this option was not advertised in the man page nor the usage page, therefore it should be okay to reuse it for -h, --headers.