guilds, closes #377

Basic guild framework and API commands. Guild perks TBD.
lint fix
sanity check on sendInvite

Prevent sending invites to nonexistent players
sendInvite return value

sendInvite now returns the invites a guild has remaining.
revisions 1

Eliminated superfluous returns, moved guild creation cost to game config
JSON
Merge pull request #407 from sadbear-/master

Guilds, closes #377