3.5.8

Added:
▪ Image placeholders can now be completely disabled in "nowebengine" RSS Guard variant. (#205)

Changed:
▪ Source code refactored, faster regexp-related operations.
▪ Optimized displaying of messages which do not have any associated URLs.

Fixed:
▪ "optimize tables" command for MariaDB now works correctly.
▪ Fixed downloading of e-mail attachments in Gmail plugin.
▪ Parsing of datetime strings now works better with Gmail plugin.
▪ Corrected logic of cleaning DB, which allows to really get rid of all messages stored in DB.
▪ Fixed crash when closing settings dialog.
▪ Message datetime decoded correctly in Gmail plugin.
▪ I hope, that appveyor/travis CI are now fixed as well.