code editor improvements and simplification

Ignore-this: 8cfafe7bc58e8b1166ee2b9ae0cb97f2

darcs-hash:20140123235042-c21fe-51b963f03a219766136ce75619af0c0443058081
cursor position in app editor remains same after new code arrives

Ignore-this: 4e3d69a47baa18215a5569b77b2d7efc

darcs-hash:20140123235420-c21fe-d9c623063c31bed9b96d680dc8ab30038e78cca1
changing app editor update to 20hz

Ignore-this: a15a54911a71f3218c4d33d49d677307

more realistic performance for messages

darcs-hash:20140123235836-c21fe-ac256d812699b25f1beafe9f723329bf60e00481