ulisp-esp32

A version of the Lisp programming language for ESP32-based boards.

For more information see http://www.ulisp.com/show?2AJI

Patches from original:

• Deleted line-editing, save-image, and load-image support
• Deleted all code not for ESP32 specifically (shorter and easier to maintain)
• Run-from-SD on startup
• Different printgcs message
• Goheeca and Max-Gerd Retzlaff's error-handling code (https://github.com/Goheeca/redbear_duo-uLisp/commit/4894c13 and http://forum.ulisp.com/t/error-handling-in-ulisp/691/7), but replaced sp_error with fn_throw (sp_error caused a segfault)
• Dave Astels' defmacro, intern, and generic :keyword support (http://forum.ulisp.com/t/ive-added-a-few-things-that-might-be-interesting/456)

New custom functions:

• battery:voltage, battery:percentage, battery:change-rate (reading from the MAX17048 on a SparkFun Thing Plus C)