eeschema, symedit: Symbol anchor used as reference point in block copy

[Sergey A. Borshch]

Steps to reproduce:
1)Open symbol in symbol editor.
2) Select block.
3) Press Ctrl-C or select "Copy block" "Cut block" but not the "Duplicate block" from dropdown menu.
4) Press Ctrl-V or "Paste" from dropdown menu.
Expected behavior: last corner of block selection rectangle used as reference point (as "Duplicate block" do). Actual behavior: symbol anchor used as reference point, which often is far away from selected block.

Version info (today's git master):
Application: eeschema
Version: (5.1.0-rc2-10-g13249b7-dirty), release build
Libraries:
    wxWidgets 3.0.2
Platform: Linux 4.4.0-138-generic x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.58.0
    Compiler: GCC 5.4.0 with C++ ABI 1009

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=OFF
    KICAD_SCRIPTING=OFF
    KICAD_SCRIPTING_MODULES=OFF
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=OFF
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=OFF
    BUILD_GITHUB_PLUGIN=OFF
    KICAD_USE_OCE=OFF
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON

[Seth Hillbrand (sethh)]

Related to lp:1800513

[Jeff Young (jeyjey)]

Paste now uses the center of the selection if it contains more than one item.