Rename test/TestSuite.hs to test/Main.hs
Add .ghci
Add `Selection`

Add type class `OTCursor` for cursor information associated to documents.
Remove the old `Cursor` and `AugmentedTextOperation` data types in
`Control.OperationalTransformation.Text`.
The new `Selection` data type can handle multiple cursors and selection.
The server implementation now handles cursor information.