Sync of ksharindam

Changelog:

4.12.1 : windows package : no longer shows choose directory page when update or reinstall
4.12.0 : added : Get Plugins option
4.11.0 : advanced check for updates feature. Can check for updates without help of browser.
4.10.6 : save as dialog : choose proper filefilter instead of All Files
4.10.5 : can open image with wrong file extension, and fix the extension
4.10.4 : photo-collage : fixed - could not embed external non-jpeg images in pdf export
4.10.3 : inpaint : remember brush size
4.10.2 : more simple stretch contrast algorithm
4.10.1 : photo-collage : fixed - on Windows photo-collage could not directly embed jpg from disk while pdf export
4.10.0 : added : adjust color levels filter
4.9.3 : added : open image from clipboard and copy to clipboard options
4.9.2 : can rotate by any angle
4.9.1 : photogrid : minimum spacing for making cut friendly
4.9.0 : added : webp support to windows and appimage package
4.8.2 : photo-optimizer : some minor ui changes
4.8.1 : photo-optimizer : adds thumbnail if photo is not compressed
4.8.0 : added : photos optimizer plugin
4.7.1 : fixed : notification TrayIcon is not shown
4.7.0 : keeps some exif data while saving jpg
4.6.2 : adaptive corner dragbox size
4.6.1 : fixed wrong tip in mask tool, changed tools icon
4.6.0 : added : text tool plugin
4.5.6 : precalculates blur radius
4.5.5 : fixed : could not read file with unicode filenames in windows
4.5.4 : added : check for updates
4.5.3 : added : mask tool
4.5.2 : untilt : added crop checkbox
4.5.1 : shows slideshow in fullscreen mode and dark background