Add navigation via arrow keys

[CWempe]

It would be nice to use arrow keys to navigate thou the topics.

Use left,/right to expand/collapse topics

[thomasnordquist]

That's a tricky one, but a nice feature.

[thomasnordquist]

Navigation via arrow key has been implemented.
Will be part of 0.3.2 (0.3.1 supports it, is only released for ubuntu snap store as part of a critical bugfix).

As part of this issue other keyboard interactions have been added:

• "Search as you type" (filter tree without previously selecting the search bar)
• Broker profile selection with ↑ and ↓, connect with ⏎ Enter, abort connection with Esc and ⏎ Enter
• Tab element selction order has been imroved
• Fix range selection with Tab in Chart settings
• Navigate tree with ↑, ↓, ←, →.
  Delete (retained) topics / partial trees with Del or Backspace

Missing:

• Split-view cannot yet be controlled via the keyboard

[thomasnordquist]

Released with v0.3.5.