Feature request: handle RestructuredText & Markdown according to spec

[bendavis78]

I still find it somewhat difficult to use vim-tabular when creating Markdown tables, and especially with RestructuredText tables. The main problem, I think, is how to handle the "separator rows". Each form has its own quirks. I imagine most of the code for making this work in is there, but I'm not sure.

In RST, you make a table like so:

+------------+----------+----------+ 
| Header 1   | Header 2 | Header 3 | 
+============+==========+==========+ 
| body row 1 | column 2 | column 3 | 
+------------+----------+----------+ 
| body row 2 | column 2 | column 3 | 
+------------+----------+----------+ 

In this case, using :Tabularize /[|+] seems to work ok, but the --- and === rows do not get filled in.

The alter form for RST is like so:

Header 1    Header 2  Header 3  
=========== ========= =========
body row 1  column 2  column 3  
body row 2  column 2  column 3  

The issue here is that columns are determined by the === header row, not the content of the columns themselves. In both cases column width is determined by the header rows.

In markdown tables are done like so:

| Header 1   | Header 2   | Header 3  | 
|============|============|===========|
| body row 1 | column 2   | column 3  | 
| body row 2 | column 2   | column 3  | 

Running `:Tabularize /| works well enough, but again the header separator does not get filled out.

Is there a solution to handle these cases already, or would it be a lot of work to build in add-ons for these special table syntaxes?