minor and major reworks: rename swb to SRU, add a test for pdf parsing

major: rework mail to send mail as plaintext instead of html, preventing the bleed-in of html text

src/ui/widgets/elsa_main.py

@@ -7,8 +7,8 @@ from PySide6.QtCore import QDate
 from PySide6.QtGui import QRegularExpressionValidator
 
 from src import LOG_DIR, Icon
-from src.backend import Database, Semester, recreateElsaFile
-from src.logic import Prof, elsa_word_to_csv
+from src.backend import Database, recreateElsaFile
+from src.logic import Prof, Semester, elsa_word_to_csv
 from src.ui.dialogs import ElsaAddEntry, popus_confirm
 from src.ui.widgets.filepicker import FilePicker
 from src.ui.widgets.graph import DataQtGraph