mark in register and move to register needs implementing

[aks]

VI (VIM) has "mark" the current position to a register (a..z) and a "move" to the current line or position in a register.

To mark the current position:

m<letter>

To move the cursor to the previously marked line:

'<letter>

To move the cursor to the previously market position (at the line and column):

`<letter>

Examples:

mz                               -- mark the current position into the "z" register
/find something
/find something else
'z                                  -- go back to the previous position