#16 memory refactoring

[Csaba Skrabák]

Use VIC bank from 32768 (#1). Set screen memory pointer (@648) too, to enable blinking-cursor input. Basic memory top could rise up to K36.

POKE56,136:CLR:REM BASIC MEM TOP K34-1

REM COPY CHAR MEM TO 34816
...

POKE56576,PEEK(56576)AND 252 OR 1:REM VIC BANK 1 (FROM K32)
POKE53272,99:REM SCREEN MEM=38912, CHAR RAM=34816
REM FOR 2ND CHAR RAM: POKE53272,101
POKE648,152:REM BASIC SCREEN=SCREEN MEM