Initial and trailing whitespace is inconsistently not preserved

[panglesd]

Let me give a few examples (using docstring comment syntax) of the current behaviour:

#	Original	Corrected
1	{[ 1+1 + 2 ]}	{[1+1 + 2]}
2	{[ 1+1 + 2 ]}	{[1+1 + 2 ]}
3	{[ 1+ 1 + 2 ]}	{[ 1+ 1 + 2 ]}

• In 1, both initial and trailing spaces are removed, while in 2, only initial spaces are removed
• the outputs on1 and 3 also feel very inconsistent...

While this is not a huge problem (one can consistently adopt a non-spaced {[content]} layout), I think it would be good to let the user decide, as for instance {[content]}, {[ content |} and

{[
   very long content
]}

make sense to use.

Moreover, I would like to introduce the use of mdx to check that the examples given in a library compile, and this is generating a lot of diff.

[panglesd]

This can also interact with ocamlformat when parse-doctring is set to true!