- refactored the slickgrid copymanager code to fit the new slickgrid code design

- TSV (Tab Separated Values) text-only format is stored in the clipboard when you hit Ctrl-C key

- grid cell formatter has been adjusted to also output plaintext, as is required of all slickgrid formatters (cellMetaInfo::outputPlainText = true)

- add SHIFT, etc. keycodes to Slick.Keycode.

- Note: Yes, I'm aware slickgrid Copy/Paste behaviour is also relying on keyboard event bubbling/propagation all the way to the 'default handler = browser native'

- sync slickgrid code with lib: rigorous application of Slick.Keyboard.*, etc.