The RUN commands (T, TP, P, G) and the RE command use the RE command
buffer to run commands. Most commands are allowed to be run from the
RE buffer. Disallowed commands include program-loading L, A, E that
switches the line input mode, TSR, Q, Y, RE, and further RUN commands.
When the RE buffer is used as input during T, TP, or P with the
SILENT keyword, commands that use the auxbuff are also disallowed and
will emit an error noting the conflict.

RE.LIST shows the current RE buffer contents in a format usable by
the other RE commands. RE.APPEND appends the following commands to
the buffer, if they fit. RE.REPLACE appends to the start of the
buffer. When specifying commands, an unescaped semicolon is parsed
as a linebreak to break apart individual commands. Backslashes can
be used to escape semicolons and backslashes themselves.

Prefixing a line with an @ (AT sign) causes the command not to be
shown to the standard output of the debugger when run. Otherwise,
the command will be shown with a percent sign % or ~% prompt.

The default RE buffer content is @R. This content is also
detected and handled specifically; if found as the only command
the handler directly calls the register dump implementation
without setting up and tearing down the special execution
environment used to run arbitrary commands from the RE buffer.
