Detect qt5ct and workaround it (#198)

* Detect qt5ct and workaround it

The documentation of python's `os` module recommends modifying `os.environ`
directly, rather than using `os.unsetenv()`. (Modifying the former causes
the latter to be called; using the latter doesn't update the former.)

lisp/main.py

@@ -21,7 +21,7 @@
 import logging
 import sys
 from itertools import chain
-from os import path
+from os import environ, path
 
 from PyQt5.QtCore import QTranslator, QLocale, QLibraryInfo
 from PyQt5.QtGui import QFont, QIcon
@@ -63,6 +63,11 @@ def main():
         level=log
     )
 
+    # Detect qt5ct (icons do not appear when qt5ct is installed)
+    if 'QT_QPA_PLATFORMTHEME' in environ and environ['QT_QPA_PLATFORMTHEME'] == 'qt5ct':
+        logging.warning('qt5ct detected. Linux Show Player and qt5ct are not compatible. Overriding.')
+        del environ['QT_QPA_PLATFORMTHEME']
+
     # Create the QApplication
     qt_app = QApplication(sys.argv)
     qt_app.setApplicationName('Linux Show Player')