[FR:] `/plot setowner(s)` | `/plot addowner(s)` & `/plot removeowner(s)`

[supercrafter333]

I saw that CPlot haven't implemented commands like /plot setowner(s) | /plot addowner(s) & /plot removeowner(s) yet.
Plot-Owners cannot add or remove owners at this time, but I think the most CPlot users would be very happy about these commands.
I think it would be very usefull to add these commands.
These commands should also merge the owners from merged plots.

[ColinHDev]

I think, I will address all of that in a single PR, which will probably include:

• /p setowner as an admin command, to set the owner of a plot
• Maybe /p addowner for plot owners to add other players as owners
• Not /p removeowner: Being the plot owner obviously means you own the plot. So there won't be a feature for plot owners to remove other plot owners. If someone is an owner, he will stay that unless an admin decides to change that.
• /p give, although I am not sure what to do if a plot has multiple owners. Maybe those others need to accept with /p give ColinHDev confirm
• Change /p merge, so admins can merge plots with different owners, with both of them becoming owners of the plot. Maybe, also allowing normal players to merge plots that they do not own and only merge if the other's plot owners accept with p merge ColinHDev confirm