Fix restore function

[florian-hofer-ipe]

Problem:

• the restore file is loaded into the new buffer
• the eeprom_fields of the old buffer are decoded into ee
• ee is patched in place via process_args
• if erase_eeprom == 0 ee is applied to the new buffer => this results in new and old always being identical

Solution:

• if file_path decode ee form new buffer
• else decode ee from old buffer

Positive side effect:

• while restoring from file the eeprom fields can still be patched on the fly