Fixed some niggling problems.

- Handled case where texarea has no line-height.

- Added 'word-wrap' style to shadow textarea; height calculation for long lines of text with no spaces behaves better.

- Added detection for enter character in keydown event which inserts a '<br />' to the shadow html.  This means no more flicker on enter key presses.

- Added a '...' to the end of shadow when noFlickerPad is zero; this causes an extra line to appear when getting close to causing a wrap.  No more flicker on text wrap.