Short term:
- Allow more complicated conditional expressions

Medium term:

- LINE INPUT
- Read and write Files (PRINT #...)
- STOP command
- CLS/CLEAR? (Curses? Lots of \n's? \e[2J?)
- YETI (needs only LINE INPUT? Or also file handling?)
- Basic_Print & Basic_Input subs for output_perl, so that when you translate
  a program into Perl, the I/O is more like BASIC's. (May be Hard, actually.)
- Upgrade test suite
- Update termbasic (NEW, LIST, etc.)
- other intrinsic functions: tab, sqr...
- upgrade error handling (Carp, etc.)
- Upgrade basic.pl & other scripts, possibly include switches (and pod!)
- Improve pod for LB & its subpackages

Long term:

- output BASIC, debug BASIC code
