Avoid creating a whole new claim when resizing

[WesternIcelander]

• Resizing a claim no longer creates a new claim object, but reuses the existing one.
• Also fixes ClaimCreatedEvent when a player resizes his/her claim. ClaimCreateEvent fired when resizing a claim #455

[bigpresh]

This looks sensible, and simplifies the code a bit too, so I'm in favour.

My only slight concern is breaking compatibility if there's any third party code out there which uses createClaim() to set up claims automatically and could be tricked by the change of meaning of the last parameter, but I find it fairly unlikely that anyone is doing that, and documenting the change in the changelog is probably enough.

Also - I'm not sure dryRun is the best name, but I can't think of anything definitely better - saveClaim or something, maybe (with the logic negated), but that's only a really minor thing, and I don't object strongly at all :)

[RoboMWM]

Looks okay. I'm guessing the isNew boolean was from @Narimm's PR.

Found an issue I think

[RoboMWM]

nvm it's okay I guess. Unsure why result was used instead of just resaving the already-existing claim but ok.