Implement left and right shift in insert state (fix #258)

C-t and C-d are bound by default to `evil-shift-left-line` resp.
`evil-shift-right-line` in insert state. These two functions simply
call `evil-shift-left` resp. `evil-shift-right` with the current line
as region.
Update list of authors
Add name of Lintaro Ina
Ensure :global generates a single undo step
Merge stable