New key bindings for commands

Existing Ctrl+Shift+I and Ctrl+Shift+D key binding run with conflict
with commands with the same keybings from the Eclipse Platform and other
plugins.

This patch proposes new keybindings:
  - Select All Occurrences: Alt+F3 (Win, Linux) / Ctrl+Cmd+G (Mac)
  - Select Next Occurrence: Alt+J (Win, Linux) / Ctrl+G (Mac)
Merge pull request #17 from kaloyan-raev/hotkeys

New key bindings for commands