FEAT: added FUNCTION constructor support to the interpreter.
FEAT: added /extern option support to FUNCTION for the interpreter.
FIX: chained infix expressions not returning correct value when last expression in a block (interpreter).
FEAT: added refinement! literal syntax support to tokenizer (LOAD).
FEAT: added support for path! and lit-path! to runtime lexer (LOAD).

Set-path! support is pending.
FEAT: added support for set-path! in runtime lexer (LOAD).
FIX: compiler was relying on obsolete `eval-path` function specification.
FIX: issue #422 (FUNCTION: invalid /extern values)
FIX: issue #425 (Interpreter FUNC doesn't take return spec)
FIX: issue #423 (Lexer crash on malformed path)
FIX: issue #424 (LOAD doesn't strip comments)
FIX: stack corruption occurred sometimes on infix expression.

The cause was unbalanced stack frames opening/closing, now only one open-frame is issued and only one close-frame for an infix expression (simple or chained).
FIX: adjusting back stack's underflow detection barrier to a stricter test.
FEAT: added support for literal negative integers to runtime lexer (LOAD).
FIX: better handling of minus sign.
FIX: path with negative integers loaded as block instead of path by the runtime lexer (LOAD).
FIX: interpreter crashing on `function [] [()]`.
FIX: character / used a word was parsed as a refinement (regression).
FEAT: added issue! support to runtime lexer (LOAD).