Implemented Jit compilative pointers to variables.

Implemented two commands: 'popptr var', 'pushptr var'.
First command - 'pushptr' pushes adress of the command's
argument to stack.
Second command - 'popptr' pops top of the stack to the variable
pointed by adress in the argument.
Simple example:
| declare  var | Declare two variables - "var" and "ptr"
| declare  ptr |
|              |
| pushptr  var | Variable 'ptr' contains pointer to
| popto    ptr | variable 'var'
|              |
| push     0   | Variable 'var' is equal to 0
| popto    var |
|              |
| push     1   | Equate veriable that pointed by adress
| popptr   ptr | in variable ptr to 1
|              |
| pushfrom var | Print value contained in the variable 'var'
| top          |
Programm's output: 1