Hi RoyiA,
Yes, there is already a portable edition up on the download page. I placed all the Qt libraries and the ghostwriter executable into a folder and zipped it, so you can take it with you to any Windows machine. Also, ghostwriter does not write its settings to the registry. In the portable edition, they will be written to the data folder within the ghostwriter folder, including new themes you create.
If you want to do the same on Linux, just build it, create a data folder in the same folder as the ghostwriter executable, and likewise put Linux Qt libraries into the folder (unless these already exist on the machine on which you will be running it). It will store settings to the data folder you created, rather than to ~/.config.
Happy writing!