Reorganize Level and Script Editor UI actions

[tommai78101]

Redesign the Script Editor UI, so that only:

• 1. Level Editor can save and load both map area and script files.
• 2. Level Editor determines where to save/load the map area and script files from.
• 3. Level Editor should allow the user to save/load the map area from the official "area" directory, official "script" directory, or the all-in-one "mod" directory.
• 4. If the user chooses a directory not from these 3 places, both the map area and the script files will be saved together.
• 5. If the user chooses the "area" directory or "script" directory, then the map area will be saved to the "area" directory, and scripts to the "script" directory.
• 6. If the user chooses the "mod" directory, the map area will be saved to the "mod/area" directory, the script files will be saved in the "mod/script" directory.
• 7. When loading an area file or a script file, use the checksum to determine where the required files are at, from these places.
• 8. If no required files were detected, do not attempt to continue loading the level editor session. Throw some dialog messages or something to warn the user.