QoL improvements

• You can structure icons in the Obsidian tools panel by moving scripts to folders
  
• I added useful actions to the hamburger menu in both tray-mode and normal-mode.
  
• I added a new Export Image dialog. You can access the new export screen from the hamburger-menu
  
• Links in help now point to Obsidian-Excalidraw relevant content.
• Added a welcome screen
  
• I updated the alternative dark mode / dynamic styling script