Button Enhancements

Added TouchUp and TouchDown events.
FontSize, FontBold, FontItalic properties made visible in blocks editor.

Change-Id: Ia308344c0c660e70f777d035555f77e698d018f6
Fix minor typos in documentation for YandexTranslate

Change-Id: I6e47f1a7ba9d871249dcdb09524f9c0ff5e1227c
Update Companion Version number to 2.18ai2

Change-Id: I671b7f022cf61b156834bb52eef6dce989a3cead
adding function showdropdown
merge conflict