Released on 2022-12-27.

This is a huge release that focuses on extending the capabilities of the core
language so that non-trivial programs can be written in it.

Language changes for better control flow:

• Issue #153: Added support for labels (identifiers prefixed by an @ sign)
  and GOTO.

• Issue #155: Added support for "line numbers as labels", just like
  QuickBASIC does, which permits running the traditional 10 GOTO 10
  program. Note, however, that these line numbers have nothing to do with
  the actual line numbers in the file. To minimize confusion, line numbers
  have been removed from the output of LIST.

• Added support for GOSUB and RETURN, which provides a rudimentary
  mechanism to reuse code within a program.

• Issue #121: Added support for catching errors via ON ERROR GOTO and ON ERROR RESUME NEXT. Captured error messages are exposed to the user via
  a new ERRMSG function.

• Replaced the EXIT command with the END keyword.

• Added support for DO loops with optional UNTIL/WHILE pre- and
  post-guards and EXIT DO early terminations.

• Added support for uniline IF statements.

• Added support for SELECT CASE.

• Fixed END so that it works in the context of WHILE loops and so that
  no further expressions are evaluated in FOR and `IF statements.

• Rewrote the execution interpreter to be bytecode based instead of walking
  over the AST.

Language changes for better numeric handling:

• Issue #114: Added transparent promotion from integers to doubles and
  automatic rounding of doubles as integers.

• Issue #114: Added support for doubles in FOR iteration, both to specify
  the loop range and the step.

• Added support for the exponent (^) operator and the SQR function.

• Added syntax to specify integers in different bases, using forms like
  &b_1010, &d_1234, &o_750, and &x_12f.

• Extended AND, NOT, OR, and XOR to perform bitwise operations when
  operating on an integer context and added the << and >> bit shift
  operators.

Standard library changes:

• Issue #114: Removed the DTOI and ITOD functions now that integers and
  doubles are automatically converted between them, and added the CINT and
  INT functions.

• Issue #114: Removed the MAXD/MAXI and MIND/MINI duality in favor of
  simpler MAX and MIN functions that can mix and match integers and
  doubles.

• Changed the syntax of the MOUNT command to take advantage of the AS
  keyword as an argument separator and thus be of the form
  MOUNT target$ AS $drive_name$.

• Fixed PRINT so that, if the statement ends in a comma or in a semicolon,
  no newline character is printed. Useful to construct output lines in
  multiple steps and matches the behavior of other BASIC implementations.

• Issue #154: Added support for the DATA statement and the READ and
  RESTORE commands. Booleans, numbers, and strings are supported, but
  strings must be double-quoted (as opposed to other BASIC implementations
  where the double-quoting is optional).

• Added the ASC, CHR, and STR functions.

• Renamed DEL as KILL to match QuickBASIC and avoid confusion with a
  potential future DELETE command implementation.

• Fixed INPUT so that the prompt is optional and thus things like
  INPUT var work as they do in traditional BASIC implementations.

• Issue #108: Added the SCRROWS and SCRCOLS functions to query the size
  of the textual console and the GFX_HEIGHT and GFX_WIDTH to query the
  size of the graphical console.

• Added the GFX_CIRCLE and GFX_CIRCLEF commands to draw circles.

Usability improvements and fixes:

• Issue #113: Added line and column tracking to error messages for parsing
  and execution errors. Also cleaned up Rust Debug impls that leaked
  into strings to provide nicer error messages.

• Issue #111: Added support to interrupt running programs via CTRL+C.

• Extended the builtin language documentation to explain in detail every
  statement type. HELP "LANG" now displays a collection of topics to
  choose from, instead of a one-page cheat sheet.

• Added the PALETTE.BAS demo, which is a little tool that renders the
  full color palette.

• Changed the syntax to call argument-less functions, such as INKEY and
  PI, so that they do not accept (). This matches traditional BASIC
  implementations.

• Fixed erratic insertion of newlines in existing text in the editor.

• Modified the HELP command to only accept a string as its argument
  instead of also recognizing a bare word. The latter was only approximate
  and would cause confusion when typing something like HELP DATA, as this
  resulted in a parse error.

• Rewrote the SDL console internals to use a separate thread that implements
  the SDL main loop. This fixes some rendering issues and crashes that have
  been previously observed with this implementation.

• Modified the interpreter to parse the full program before executing it,
  which was a requirement for supporting GOTOs and features like DATA.
  As a side-effect of this change, any syntax errors now cause the
  interpreted program to not run at all, as opposed to before when the
  program would make progress until it hit the error.