Merge branch 'slient-update' into development
Version 1.5
Merge branch 'development'
Update Readme
Update Readme about auto install feature
Merge branch 'master' into development
Each screen-each wallpaper changing feature and minor changes

* IsEachScreenEachSource, ScreensRects, LastUpdatedScreen added in Settings and AddtnlOptions form
* Source.LastBitmap is not changed by GetBitmap - SourceBitmap.Apply do this
* Wallpaper.SetToDesktop builds a wallpaper bitmap - not in the constructor or AddBitmap
* MultiScreenInfo.IsChanged added

* SingleInstanceProgram invokes an event to show Settings form when another instance launched
* FileUnblocker added to not show security warning for downloaded executables
* Installer and Updater unblock downloaded executables
* Preprocessors for not installation or update in debugging
Do not stretch a smaller image than a targeted screen resolution feature added

* Fix Settings.IsStretchForMultiScreen can return true in singled-monitor environment
Fix to get edge pixels only
Fix bugs and minor changes

* Fix not changing wallpaper bug
* Fix wrong painting not stretched bitmap bug
* Minor position changes in frmAddtnlOptions
Version 1.6
Update Readme
Version 1.7

* Fix a bug not able to overwrite a previous wallpaper file
* NASA Source fix
* Update Readme
Always enables 'Run on Startup' after installed
Add new try-catch not to crash when original wallpaper file is corrupt or missing
Fix National Geographic source
Merge branch 'development' into slient-update
Change GitHubUpdater to download exe from releases page