FIXED: Home/End/PageUp/PageDown in insert mode work.
Added :undo to Vim Ex mode.
Completion for Ex command 'undo'.
Vim keymap : poor-man's <C-w>←↑→↓ with prevWinE/nextWinE
Vim bindings for changing layout managers.
Vim :help shows all funs in scope, or type of a named fun.

Note that if you want more than just a type of a binding,
you might use ctags index over Yi documentation,
after examining the help index.
Remove unnecesary parens.
Merge pull request #702 from mgajda/Features

Vim keymap fixes and additions, including undo and help