Update manual or commands so behavior matches

[cheveron]

• CALL does not take parameters.
• CLEAR does not:
  • close all files.
  • mute the PSG.
  • reset the ON ERROR state
• CLOSE does not:
  • close all files if no parameter is specified.
  • work if the # is not included.
• END does not close all files.
• KEY {ON|OFF} does not do anything.
• LIST does not behave as described in the docs.
• DELETE does not match the syntax in the manual (should work like LIST).
• PRINT USING not yet implemented.
• RENUM does not behave as described in the docs.
• SCREEN is not implemented.
• SEEK is not implemented.
• SOUND should use the PSG.
• STRING$ should support characters as well as code points.
• TAB should take an optional vertical parameter (as per C64).
• WAIT should be extended to support waiting for a port input.
• DEF FN A()=FN A() causes a memory leak. Document that this will happen and to use DEF FN A()=VAL {FN A()}

[cheveron]

None of these are critical to be fixed in the penultimate beta, but they should be done before the release candidate.