Switch to a ini/git config style version check file

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Add more options to version.txt

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Allow to limit Windows versions for which to offer an update

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Provide better readable error messages

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Allow to disable update checks on update dialog

Signed-off-by: Sven Strickroth <email@cs-ware.de>