[zeditor] ZScript shouldn't prompt to save changes when no changes were made

[Asuna Yuuki Nagato]

Steps to recreate:

1. File->New
2. ZScript->Compile ZScript...; 9-button "Compile ZScript" window appears
3. Click 'Edit'; white 'Edit ZScript' window appears with #include "std.zh"
4. Press ESC
5. Observe "Save changes to buffer?" Yes/No msgbox appears

This msgbox could cause novice scripters to become paranoid that they accidentally modified their script when that isn't the case.

[Asuna Yuuki Nagato]

Similarly, we can probably skip the "Confirm Overwrite" msgbox when clicking 'Load' in that 9-button window when '#include "std.zh"' is the only thing in the buffer.