Fix Parents lost during optimization

v1.3.8

Fix #187

Fix infinite loop detection problem

v1.3.7

Updated playground

Fix problem with parsing infix expression

v1.3.6

Fix #159

Fix Packrat parsing and Infinite loop detection problems

v1.3.5

Fix #158

Performance improvement

v1.3.4

Fix #156 (#157)

Fixed `char` -> `int` conversion problem

v1.3.3

Fixed `char` -> `int` conversion problem

Fix error report problems

v1.3.2

Fixed error report problems

Support for C++17 compilers that don't have <charconv>

v1.3.1

Code cleanup

Cut operator support

Merge pull request #139 from yhirose/cut

Cut operator support

Added `optimize_ast` method and `no_ast_opt` instruction

v1.2.0

Fixed peglit problem and update README