Dimension properly code inside h1, h2,...
Proof of concept for code evaluation and solution hiding.
Adjust the colors to match those defined in the CSS file.

Some new CSS classes for code have also been added.
Ensure the color for the OCaml output is correct.
Update the minimal version required for omd.
Compile errors.mli when compiler libs are not present.
Do not eval code that hangs the process.

The most common reason is the presence of `read_line()` and infinite
loops.  Several code blocks that were not OCaml were also tagged with
`tryocaml` (there may be some left, I did not track them systematically).
Fix some misuses of ```tryocaml

Partly fixes https://github.com/ocaml/ocaml.org/issues/282
"make clean" removes all compilation generated files.
Express that "md_preprocess" depends on "code_top".
Fix COMPILER_LIBS_PREPARE when compiler libs are present.
Add dynlink to compile "code_top" for OCaml ≥ 4.00.1
Make the SOLUTION detection work with or w/o paragraphs
rework 99 problems page - lists

Refactored to fit new style of running through toplevel.
This commit completes the lists section
rework 99 problems page - arithmetic

Refactored to fit new style of running through toplevel.
This commit completes the arithmetic section
rework 99 problems page - logic and codes

Refactored logic and codes section to fit
new style of running through toplevel.
Be ready for the next version of "omd".
Properly indent code when presented with the prompt.
Remove extra space to the left of code blocks.
Show a Boolean formula in mathematical form.