#1971)

* construction line draw() method, reference entity construction line

* construction line draw() method, reference entity construction line

* refConstructionLine for preview in action

* Actions: Middle Point, Middle Line (WIP), Align, Align One

* source files layout (points)

* polygon actions refactoring, base class (WIP)

* polygon actions refactoring, base class (WIP)

* polygon actions refactoring, Polygon (Tan, Tan) action

* Align Reference Points action

* option fix

* create a copy by move (with CTRL) in default action

* setting that controls whether entities should stay selected after modification operations, changes in actions and rs_modification

* improved selection of entities for modify actions, window selection is also supported now

* preview for snap middle manual improved (for #1929)

* Draw Bounding Box action, code relayout

* BreakDivide - special handling of the case with intersection at endpoint - sometime it prevented entire entity deletion (with SHIFT)

* code cleanup

* #1968 fix

* #1957 fix

* #1959 (?) applying non-resolved pens to modified clones (so "By Layer" should not be lost after modifications)

* #1952 - dark orange color

* #1949, #1948 - orange color

* #1944 - status bar tooltips

* offset for bounding box action

* Draw Line Middle action

* Text/MText - support of ref points, dragging like other entities by ref points

* fix for #1969 - duplicated pen settings in Layer Tree dialog

* Modify Align improvement - ability to select child entities, cleanup

* fix for issue with not-removed original polyline on node append

* PR readme

* cleanup - compiler warnings (unused)

* disabled debug code

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Co-authored-by: sand1024 <sand1024@gmail.com>