Trilium-py

- fixed https://github.com/zadam/trilium/issues/3
- backspace on note tree jumps to the parent note
- fixed behavior of ctrl+click - now it toggles selection instead of just selecting

* fixed a bug where key between note and parent note wasn't unique so it was possible to create duplicate relationship (required DB upgrade!).
* added also extra checks before moving/cloning note for existing relatonship to provide nice error message
* removed loading animation which caused problems with setting initial focus on note tree after app startup
* alt-m (focus/private mode) now doesn't completely disappears the elements, instead makes them low opacity
* fixed switching between note clones in "note locations" list
* updated initial page in demo document to showcase supported formattings

* added possibility of selecting multiple notes in the tree (shift+up/down or ctrl+click) and things like copy&paste or drag and drop now work with selected items (behavior should be the same as before when working with single item).
* changed keyboard shortcut because of multi-select - shift+arrows formerly moved notes around. This is now done with ctrl+arrows. shift+up/down is now used to select multiple notes.
* better detection of tree cycles when cloning/moving notes around. Also added consistency check.
* context menu has now option to force sync for one note
* various small bugfixes

- global CTRL-SHIFT-arrows for navigation without losing focus in the editor
- CTRL-ENTER now goes from tree to editor
- tree titles are escaped for HTML
- when switching notes make sure you start at the top of the editor
- fixed pasting into note which haven't been lazy loaded yet
- fixed keyboard shortcuts for clipboard operations