This PR fixes the issue described in #146 wherein xdg-open subprocess calls will fail to launch the user-specified file-manager under frozen/PyInstaller builds on Linux. As it turns out, the PyInstaller bootloader sets a LD_LIBRARY_PATH environment variable on Linux which, for whatever reason, interferes with xdg-open's ability to locate and/or launch the desktop file-manager. Unsetting this environment variable, accordingly, corrects this behavior, allowing the file-manager to launch as expected.