Bug parsing @code blocks

[idclifford]

By default, it seems like mkdoxy just extracts the text from @code blocks and adds them to the variable/class/whatever descriptions without any markdown syntax. I think this is an issue in MdCodeBlock in markdown.py.

I tried modifying the render function as follows:

def render(self, f: MdRenderer, indent: str):
	f.write("```\n")        # NEW LINE
	for line in self.lines:
		f.write(line)
		f.write('\n')
	f.write("```\n")        # NEW LINE

This seems to fix the issue, but this breaks the source code listings that mkdoxy generates. This needs to then be fixed by updating the jinja template and removing the ```.

This seems to fix the issue, but I don't know if this is the better way to do this.