Fixes for strange behavior while typing text

[Nes-si]

These commits fixes three bugs:

1. At first typing you can see sudden increasing text field height.
2. Problems with text field updating.
   For example, you can reproduce it on a demo:

• select string
• apply "H2" to it
• set cursor to the end
• press Enter
  You will see that cursor stay in place.
  There are a lot of such strange behavior else..

3. Also there are some cases when the component receives props several times, with old and new text. I've added a handling for these.