Syntax: RESTORE [ filename ]

   Restore all the current macros, variables, and vectors from file
`filename' (if omitted the default is to use the value of `save_file'
in your .sm file, or failing that `sm.dmp'). In addition, the current
history buffer is replaced by the macro `all' if defined in the
RESTOREd file.

   The file should have been written by the SAVE or MACRO WRITE
command, or at least have a similar format.

   If verbose (q.v.) is greater than 0, some extra information is printed.