loading a xcf image with text layer fails

[Gnumaru]

I was trying to parse text from a text layer and came up with an exception while trying to load the xcf file. The message was

Exception has occurred: ValueError
invalid literal for int() with base 10: b'\x00\x00\x00\x01'

I made a new xcf file with just one layer, a text layer, named 'text' with the text 'text' in it and I had the same exception whe loading the file. The code for loading the file was the folowing:

import gimpFormats
doc = gimpFormats.GimpDocument()
doc.load(fullPath)

where 'fullPath' was a variable containing a valid file path.

Could you see if you can load a xcf image with text layer without this error? This was tested with code from the master branch, the enviroment was windows 10 x64 running python 3.7.4 x64 and the xcf file was created with gimp 2.10.12 x64 for windows

I made a pull request for a possible fix
#1