Separate release flavors from core cadesim code

[plaza-in-a-heatwave]

Problems

• Core functionality is tied to one release flavor
• Adapting to other flavors will be more difficult

Current situation:

• All code releases geared toward one flavor at the moment
• Some files (user.config, getdown.txt) are specific to the flavor
• This flavor is hosted on the repo (release branch).
• Code is deployed with ./deploy.bash flavorname which is on the main branch

Design criteria

• Core code is flavor-neutral
• Allows other flavors to be hosted on git or some other host, flexibly
• Should provide a way to build flavor-specific releases, but these should sit in a different branch.
• Should host flavor-specific backgrounds, images, overlays, but these should sit in a different branch.
• Shouldn't host flavor-specific config - this should go in an installer
• Shouldn't create installers - this should be done by the owner of the specific flavor separate to this repo.

Proposed:

• Different branches, one per flavor. e.g. flavor-growup
• getdown.txt will contain the host URL on these branches.
• user.config will be generic in the main branch and the flavor branches. It will be specific only in the installer.
• Flavors can optionally be hosted on this repo (release branch) or another host (getdown URL changes)
• specific deployment scripts on each flavor branch, e.g. ./deploy.bash rather than ./deploy.bash flavorname

Affected files/aspects:

• branching
• user.config, getdown.txt
• deploy.bash
• flavor-specific backgrounds, images, overlays

[plaza-in-a-heatwave]

user.config is no longer a required resource as of 309457d, so this may no longer need to be flavor specific. Related: #119 might result in an additional file for server config, which would be flavor specific.