HeliBoard 4.0-beta2

Changes since 4.0-beta1:

• fix numpad not recognized as number layout (#2579)
• fix incorrect bottom row height when number row was enabled (#2580)
• ignore null text input (#2608)
• yet another workaround because Firefox ignores KeyEvent.KEYCODE_PASTE (#2606)
• update outdated words in Brazilian dictionary, by @joaohcopetti
• some more fixes