override CM's default height of 300px with auto, now that the CM element controls the height of the editor
exploring CM3.1 JS changes
Merge commit 'dyoo/codemirror-3.1' into codemirror-3.1
Merging in work from retief's branch

https://github.com/retief/WeScheme/commit/9c613f81e2c866f4694c075ca5e42b509124d41d