changed Help->Online->Commands link, fixes LibreCAD#1215

refactoring of RS_DimAngular, fix LibreCAD#911 and LibreCAD#824/Libre…

…CAD#896

returning to LC via Command+Tab won't always activate a subwindow Lib…

…reCAD#821 LibreCAD#814

eliminated build error for gcc 5.4

LibreCAD@8bedeb5751ac0b3490b9d5395741
687fc774eae9

ensured that draft mode is set for new drawings; LibreCAD#749

set LC_VERSION="2.2.0-alpha"

set LC_VERSION="2.1.0"

added device options; LibreCAD#658

switched version to 2.1.0-beta

ellipse: fixed trim by amount(lengthen)