Feature/Market ui

[friedger]

This PR

• adds a new top level menu "Market"
• adds a screen of all offers
• adds actions for create offer, update offer, remove offer and claim pet.

The current flow is supported for transferring ownership (all in the market screen):

1. user a creates an offer
2. user b claims the monster Done, the monster has been transferred from user a to user b.

Note: The RAM by user A until user B interacts with the monster.

Invalid offers are shown in red. Dead monsters can be transferred as well.