Events should not be generated while client is waiting for Proceed message from server

[mkromberg]

For example, the CellMove event resulting in a successful KeyPress must never be sent until the server has said Proceed to the KeyPress. If the server rejects the KeyPress, the CellMove should be cancelled. In DemoScroll, if you move from cell [1,1] to [1,2], you will see messages in the following order:

Client sends two messages with EventID immediately:
12:31.200 R: #11: {"Event":{"EventName":"KeyPress","ID":"F1.VGRID.E1","EventID":"72346260-12a8-41a7-ab7a-6d003a186026","Info":["ArrowRight",65,39,0]}}
12:31.207 R: #11: {"Event":{"ID":"F1.VGRID","EventName":"CellMove","EventId":"a29632b6-9143-4d5d-943d-a63ac404853c","Info":[1,2,1,0,0,0,""]}}

Callback for KeyPress asking for CurCell:
12:31.238 T: #11: {"WG":{"ID":"F1.VGRID","Properties":["CurCell"],"WGID":"102"}}
12:31.241 R: #11: {"WG":{"ID":"F1.VGRID","Properties":{"CurCell":[1,2]},"WGID":"102"}}

Callback for CellMove asking for CurCell:
12:31.297 T: #11: {"WG":{"ID":"F1.VGRID","Properties":["CurCell"],"WGID":"105"}}
12:31.299 R: #11: {"WG":{"ID":"F1.VGRID","Properties":{"CurCell":[1,2]},"WGID":"105"}}

Callback for KeyPress completes:
12:31.270 T: #11: {"EC":{"EventID":"72346260-12a8-41a7-ab7a-6d003a186026","Proceed":1}}

Callback for CellMove completes:
12:31.304 T: #11: {"EC":{"EventID":"a29632b6-9143-4d5d-943d-a63ac404853c","Proceed":1}}