HeliBoard 2.0-beta2

Only few changes since the last beta, but contains a few fixes of old bugs that could potentially cause regressions.

Changes since 2.0-beta1:

• add emoji toolbar key, by @codokie (#845, #837)
• improvements regarding duplicated letters (#225 and maybe others)
• avoid positioning cursor inside emojis (#859)
• minor fixes for recently added features (#848 and more)