FORGE-1753: Support for InputType.TEXTAREA
add test for getDelegate()
add test for setCursorListener()
implement robuster version of setDocumentListener() + add test for it
add test class for StyleImpl
add test for getStyleRange()
add test for resetToNormal()
add test for setBoldOn()
add dummy test for setFaintOn()
add a test for setItalicOn()
add a test for setUnderlineSingle()
improve implementation of setImageNegative() and add test
add test for setCrossedOut()
add test for setBoldOrFaintOff()