Print hexadecimal number and wrap screen

PUTC now wraps if reach the end of the screen
Added PUT_UHEX, PUT_UWHEX and PUT_UBHEX to display hexadecimal numbers
Filtering from keyboard input

Avoids strange output on screen and sanizate parser input.

Filter should make more easy a parser with this commands :

 * [0-9a-fA-F]+ : Hexadecimal value/address -> Display byte at these address
 * val[rR] : Run at address val (CALL val)
 * [rR] : Run at last address introduced
 * val1.val2 : Display values from val1 to val2
 * .val2 : Display values from last address introduced to val2
 * val: value_list : Puts data begining at address val
 * : value_list : Puts data begining at last address introduced