Don't show message about not using "Vim" keymap any longer in new installations
VIM-667 Ignore potentially nested lines of .vimrc based on leading whitespace
Added notes about keyboard shortcut conflicts and .vimrc files
VIM-666 Ignore characters after '|' in :map commands

Perhaps it should become a part of command parsing, since it is
possible to put several command on one line.
Extracted Vim typed special keys map
VIM-666 Support <Bar> in Vim key notation
VIM-670 First character of a recursive mapping shouldn't be mapped again

The mapping's "from" keys should be a prefix of "to" keys.