More Main Menu Content

[Jade-Harleyy]

This PR adds:

• Buttons for the remaining content editors to the main menu.
• Singleplayer mission/sandbox modes (latter accessible by selecting no available missions for the former).

New Localization Tags:

• leveleditorbutton - Level Editor
• particleeditorbutton - Particle Editor
• eventeditorbutton - Event Editor
• spriteeditorbutton - Sprite Editor
• newmissionbutton - Start Mission

Modified Localization Tags:

• campaignlabel - Campaign => Singleplayer
• newgamebutton - New Game => New Campaign
• loadgamebutton - Load Game => Load Campaign

[EebleSheembl]

Need

[PanmanS]

This would significantly simplify testing for specific missions when quickstart doesnt suffice and serve lobby is too long to load

[Regalis11]

Buttons for the remaining content editors to the main menu.

I don't think all of these should be included in the main menu. Many of them are not intended to be used the average player, but rather advanced modders who are expected to be able to access them using console commands. If we were to make them visible in the main menu, we would need to localize all the texts in them to all the languages the game supports, and preferably also make them a lot more user-friendly.

I also feel a little iffy about including the mission mode in the main menu like this. The mission mode is so underdeveloped that in my opinion it needs to be reworked before it's put into the spotlight like this.

[NotWendy]

When I was getting into the game around 1.0, I used the mission mode as a training tool, to understand the very basics of the game, in addition to doing some of the tutorials. It may be underdeveloped right now, but it still works well enough for that purpose, allowing a new player to learn the ropes and fail in a low stakes environment.
I understand you don't want players to get the wrong impression of what the mission mode is supposed to be by trying it out before its big overhaul happens. But with the value it already brings to the game, I think you can consider adding it to the main menu early.

[WrillWasTaken]

This would significantly simplify testing for specific missions when quickstart doesnt suffice and serve lobby is too long to load

wouldn't the better solution be to just add difficulty, bot count and biome to the quickstart command?