Preserve inline diff

In GLFM, we can define inline diff in the following ways:

Tag	Type	Syntax
Diff (addition)	Markdown	{+added+}
Diff (deletion)	Markdown	{-deleted-}

We should preserve markdown / HTML style when any of these styles are used. Meaning, when the comment/page is saved, the original style of formatting is preserved.

But probably in this case, no preservation is necessary.