Instead of forcing table cells to only have a single paragraph as
their content, we now check whether they end in a paragraph (and
insert one if necessary) during #prepForXml
These errors only arose because I didn't run `npm build`, only `npm
test`. Then, when I tried building the null checks failed. Keeping the
two config fiels in sync will help prevent this issue in the future
This change brings increased type safety to uses of
XmlAttributeComponent. Now the compiler is checkign for us that the
properties that get passed in to every subclass match the intended
interface, and also that the xmlKeys property -> xml attribute mapping
has all the right keys
I checked the spec, and "w:pPr" does not take any attributes. I also
converted the paragraph tests to use the deep.equal style to get rid
of some more jsonify!
From the TypeScript manual "In strict null checking mode, the null and
undefined values are not in the domain of every type and are only
assignable to themselves and any (the one exception being that
undefined is also assignable to void)."
In other words, this setting means the compiler will complain if you
try to use a variable, but it might be null or undefined. Since the
project builds and tests pass with it, I think it's good to turn it
on. If it becomes annoying, you can always turn it off later
