Added party alliances

Adds the following commands:
`/party alliance`
`/party alliance invite <target>`
`/party alliance accept`

Allies will share party chat and will not be able to harm eachother.
Item and XP sharing is limitied to a single party. Allowing two parties
to team up without sharing resources and XP.

Closes #1009

src/main/resources/locale/locale_cs_CZ.properties

@@ -366,7 +366,7 @@ Commands.GodMode.Disabled=[[YELLOW]]mcMMO Godmod vypnuty
 Commands.GodMode.Enabled=[[YELLOW]]mcMMO Godmod aktivovan
 Commands.GodMode.Forbidden=[mcMMO] M\u00f3d B\u016fh nen\u00ed povolen v tomto sv\u011bt\u011b (pod\u00edvej se do Povolen\u00ed)
 Commands.Inspect=<player> [[RED]]- Shl\u00e9dni detailn\u00ed informace o hr\u00e1\u010di
-Commands.Invite.Accepted=[[GREEN]]Pozvanka prijata. Pridal jsi se k party {0}
+Commands.Party.Invite.Accepted=[[GREEN]]Pozvanka prijata. Pridal jsi se k party {0}
 Commands.Invite.Success=[[GREEN]]Pozv\u00e1nka \u00faspesne odesl\u00e1na.
 Commands.Leaderboards=<skill> <page> [[RED]]- Tabulka nejlep\u0161\u00edch
 Commands.mcc.Header=[[RED]]---[][[YELLOW]]mcMMO P\u0159\u00edkazy[[RED]][]---
@@ -419,8 +419,8 @@ Commands.Party.None=[RED]]Nejsi v zadne party.
 Commands.Party.Quit=[[RED]]- Opustil jsi svoji aktualni partu
 Commands.Party.Teleport=<hrac> [[RED]]- Teleport ke clenovi party
 Commands.Party.Toggle=[[RED]]- Zapnout party chat
-Commands.Party1=[[RED]]- Vytvo\u0159en\u00ed nov\u00e9 party
-Commands.Party2=[[RED]]- P\u0159ipoj\u00ed se k hr\u00e1\u010dov\u011b part\u011b
+Commands.Party.1=[[RED]]- Vytvo\u0159en\u00ed nov\u00e9 party
+Commands.Party.2=[[RED]]- P\u0159ipoj\u00ed se k hr\u00e1\u010dov\u011b part\u011b
 Commands.ptp.Enabled=Teleportace paret [[GREEN]]zapnut\u00e1
 Commands.ptp.Disabled=Teleportace paret [[RED]]vypnut\u00e1
 Commands.ptp.NoRequests=[[RED]]V tuto chv\u00edli nem\u00e1te \u017e\u00e1dne po\u017eadavky o teleport