Fix bug with 'E' and map <CR> in insert mode

<CR> in insert mode will move to the same column in the next line,
if Replace or virtual Replace mode is active. This should provide a
better spreadsheet like behaviour.

'E' in normal mode would always jump to the end of the prevous column,
while I think it is more logically, go have it jump to the beginning of
the previous column.
small improvements for column replace mode