Fix sceditor to use editor height settings

Signed-off-by: scripple <github@scripple.org>

It turns out that setting height:100% on sceditor makes it ignore the existing size of the textarea so changing the height setting in the context doesn't do anything.  However not passing a height tells sceditor to take the height of the existing textarea.

Although the size is the TOTAL size including the toolbar and grip, so really the textarea is quite a bit smaller than the specified height.