Add changelog file and restore old changelog (might have overwritten parts)

• Port to RGtk2
• internal switch to rqda_txt and rqda_sel, rqda_exe functions
• Code cleanups
• roxygen support Roxygen #3
• pkgdown support pkgdown #6
• Keystrokes for various parts (Ctrl+s, ctrl+w, crtl+q)
• import of multiple files
• assume encoding of imported files and always import as utf8
• use CI Fix appveyor #1
• write unittests Unittests #2