Export and linux build fixes (LAST Gd4.0 update NOT Gd4.1)

Changelog v2.3📰 (thanks to #31 by @vaartis)

• Fixed discord_game_sdk sometimes not copying
• Fixed linux version not building on some distros

Full Changelog: 2.2...2.3

Small quality fix

Changelog v0.2.2📰

• Editor Presence now updates more
• Fixed bug that the export plugin didn't copy the sdk on some systems

🚨 Important random crash fix 🚨

Changelog v0.2.1📰

• Fixed random crashes for both editor and running projects
• Fixed wrong large image hovertext for the editor richpresence

🎈🎉0.2.0🎉🎈

Big releases take a bit long because i try to give the user the best GDScript experience I can and i don't just implement C++ code 1:1.
This release got bigger than i thought so there is 0.3.0 already in work with relationship_manager more EditorRPC settings and more.
And thanks for 33 Stars! But now to the changelog! :)

Changelog v0.2.0📰

• Rename singleton from Discord_Activity to discord_sdk
• Added methods, singletons and variables for creating, sending and managing invites
• Now beeing able to get the current user as a Dictionary
• Beeing able to interact with the Discord overlay (only visible on OpenGL)
• Now you can register steam and launch commands
• Added custom node DiscordSDKLoader (please ignore)
• Added custom Debug node
• Added a optional RPC for the Editor wich switches between the Activity when your game launches and when you are just in the editor (sometimes it doesn't change on clientside but for your friends it does i promise) To enable it enable advanced project settings and search for DiscordSDK

I shouldn't do that much unstable updates

Changelog v0.1.5📰

• fixed #18

Fixes over fixes

Changelog v0.1.4📰

• Reverted "Fixed requirement for app_id when wanting to use other functions" (worked for someone but not always for everyone)
• Fixed addon not working in other locations then the addon folder on the root of projects

Hopefully last bugfixes before "2.0"

Changelog v0.1.3 📰

• Fixed crash when app_id is unset (#3)
• Fixed requirement for app_id when wanting to use other functions (usefull in the future e.g. getting usernames in 2.0)
• Some background improvements

Linux support

Changelog v0.1.2 📰

• Added Linux support
• Added example.gd

Fixed common crash

Changelog v0.1.1 📰

• Fixed crashing when Discord isn't running
• Automatically copies the Discord Game SDK "shared object" on export
• Added Discord_Activity.get_is_discord_working() wich shows if the function wich
  happens on Discord_Activity.set_app_id() worked / the Discord Client answered

First Release!! 0.1.0

Set details, state, timestamp and images in a discord activity.
More features from the Discord Game SDK will come very soon!