Merge branch '2511_simplify_keybindings'
* 2511_simplify_keybindings:
Symbolic names of keymap sections are defined.
Change hardcoded definitions of default keymap.
Allow remove key with empty value from target config.
Prepare to merge default and user-defined keymaps.
Added --nokeymap command line option to disable load keybindings from file.
Define keybind numbers using enum.
Fixup of shift-arrow mark in editor.
Unification of keybinding names.
Ticket #2511: simplification and unification of keybinding names.