v2.7.0

Updated to Shen Open Source Kernel 22.1

Changed

• Reintroduced backend written in Shen.
• Moved everything in the compiler from the shen namespace to shen-cl.
• Command-line handling has been replaced by the "launcher" kernel extension.
• do expressions now get compiled into PROGN expression, making them tail-call optimization friendly.

Added

• Integrated "features" kernel extension.
• Integrated "launcher" kernel extension.
• Integrated "factorise-defun" kernel extension optimization.
• Source release which includes a pre-compiled backend.lsp file.
• shen-cl.lisp-true? to convert from CL to Shen booleans (counterpart to shen-cl.true?).