v1.3.0

Full Changelog: v1.2.0...v1.3.0

make parse error messages much readable

Sample error message:

error: Invalid Terminal: '*'
Expected one of: ' ', '(', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9'
-------------------------------Backtracing state--------------------------------
M -> M '*' • M
-----------------------------------Prev state-----------------------------------
M -> M • '*' M
-----------------------------------Prev state-----------------------------------
A -> • A '+' A
A -> A '+' • A
A -> • M
M -> • M '*' M
-----------------------------------Prev state-----------------------------------
A -> A • '+' A
-----------------------------------Prev state-----------------------------------
A -> • A '+' A
E -> • A
Augmented -> • E '\0'