Fix some problems.

* Use the SQLite provided by MSYS2.
* Run regedit as administrator.
Use the new EasyOptions API.
Use single-quoted strings.
More idiomatic Ruby code with rubocop.
Fix cleanup of recent files in Word Viewer.
Add git and rubocop configuration to backup.
Update installation of EasyOptions.

EasyOptions is not installed in MSYS2 anymore since a pacman package is now available. Ruby library path is now configured when installing EasyOptions to default location in other systems, so easyoptions.rb can be used by Ruby scripts.
Fix usage of the new EasyOptions API.

This is a residual change for revision 279.