enhancement / nice to have: store offsets in hex in the project file

[binary1230]

One important goal for me is having some human readability in the XML file, so that when changes are being diff'd in git/github/etc, it's possible to have a good shot at reviewing what the changes were.

Right now we're storing offsets in base 10 (which is fine), but I think it'd be easier for humans if we stored in hex.

Here's an example of a label in the XML:

<sys:Item Key="12661979">	       
<Value Name="fn_battle_init" Comment="" />
</sys:Item>

It's more obvious to a reader that this is a ROM address if it looks like this instead:

<sys:Item Key="$C134DB">	       
<Value Name="fn_battle_init" Comment="" />
</sys:Item>

could support any or all of:

$C134DB or 0xC134DB or even $C1/34DB

that makes a lot of sense too when it's a RAM label like $7E/0001

[binary1230]

vaguely dependent on: https://github.com/ExtendedXmlSerializer/home/issues/509