Performs a big clean-up with operations like closing files and their buffers, resetting variables and re-initializing matrices, clearing the stack memory area and optionally resizing it
Implemented by: ansifull, Altair, Applesoft, level2, trscolor, colormc, Sinclair, BBC, GWBASIC, bwbasic, bw32, QBasic, VBDOS, FreeBASIC, minibasicjs, EndBASIC
With variations: tasc (does not clear COMMON variables; can be combined with COMMON and CHAIN), TI994 (through CALL), msatari, Atom (Clear Graphics Screen)
Also written as: