sgc fix

[EpicKnarvik97]

As an alternative to Stargate validation for removing Stargates, it could make sense to be able to fix Stargates. This could be accomplished through a /sgc fix command.

This change requires gate designs to be available through the API, and is therefore postponed.

The basic idea: Use a Stargate's gate design to find which blocks should be placed where, and replace any invalid blocks.
If a material tag is used instead of a material there should be some ways to handle this:

1. Choose some random material. This should be the fallback if other methods fail.
2. Optionally store the used material when a new Stargate is created (in a database, or just as YML). This would make it possible to perfectly restore the Stargate, but would take some additional storage space, and might be inefficient for huge Servers.
3. Do a pattern analysis to figure out what's been removed. This requires looking for symmetry and antisymmetry (and possibly other types of patterns) and filling out the missing blocks.

Number 3 can be seen as an additional feature and is not required.
The config should allow switching between 1, 2 and 3.