(https://github.com/ruby/irb/pull/449)

* Seamlessly integrate a few debug commands

* Improve the break command support

* Utilize skip_src option if available

* Add step and delete commands

* Write end-to-end tests for each debugger command

* Add documentation

* Add backtrace, info, catch commands

https://github.com/ruby/irb/commit/976100c1c2

Based on this commit: https://github.com/ruby/irb/commit/93f87ec65344b44123b0150a5fc07de1fd4c80c4

It appears that the maintainer @aycabta wanted to deprecate any `USE_*LINE` configs in favor of
`USE_MULTILINE`. So we should deprecate `USE_RELINE` as well.

https://github.com/ruby/irb/commit/478f19f3ae

(https://github.com/ruby/irb/pull/430)

* Support non-string input in show_source

* Test show_source as a method

(https://github.com/ruby/irb/pull/426)

* Allow non-identifier aliases

* Move the configuration to IRB.conf

* Avoid abusing method lookup for symbol aliases

* Add more alias tests

* A small optimization

* Assume non-nil Context

* Load IRB.conf earlier

https://github.com/ruby/irb/commit/e23db5132e

* Use local_variables for colorize, code_block_open check, nesting_level and assignment_expression check

* Check if expression is an assignment BEFORE evaluating it. evaluate might define new localvars and change result of assignment_expression?

* Add local_variables dependent code test

* pend local variable dependent test on truffleruby

code_block_open is not working on truffleruby

* Always pass context to RubyLex#lex

* Rename local_variable_assign_code generator method name

* Add assignment expression truncate test

* Add Context#local_variables and make generate_local_variables_assign_code more simple

* Update lib/irb/input-method.rb

Co-authored-by: Stan Lo <stan001212@gmail.com>

* Add a comment why assignment expression check should be done before evaluate

https://github.com/ruby/irb/commit/c8b3877281

Co-authored-by: Stan Lo <stan001212@gmail.com>
Co-authored-by: Takashi Kokubun <takashikkbn@gmail.com>

https://github.com/ruby/irb/commit/e58a3c1b39

Deprecates IDB::ReidlineInputMethod and USE_REIDLINE in favor of
IRB::RelineInputMethod and USE_RELINE. The Input method uses Reline to
read input from the console, so it can be named directly after the
Reline library like other inputs methods are (Readline, Stdio, etc.).

https://github.com/ruby/irb/commit/5bcade7130

They were introduced around 20 years ago, when Thread is not yet
stabilized. So we don't need them anymore.

https://github.com/ruby/irb/commit/4c75e03b2b

Also add --script option to turn the option back on.

Previously there wasn't a way to get an interactive IRB session
and access arguments provided on the command line.

Additionally, handle `-` as script as stdin. In Unix-like tools, `-`
means to take standard input instead of a file.  This doesn't
result in exactly the same output for:

```
echo 'p ARGV' > args.rb; irb args.rb a b c
```

and

```
echo 'p ARGV' | irb - a b c
```

Due to how irb handles whether stdin is a tty.

However, this change allows use of `-` as a argument, instead of
giving an unrecognized switch error. This required some small
changes to context.rb (to handle `-` as standard input) and
input-method.rb (to have FileInputMethod accept IO arguments in
addition to strings).

Implements [Feature #15371]

https://github.com/ruby/irb/commit/4192683ba2

* Use colorable: argument as the only coloring control

* Centalize color controling logic at Color.colorable?

There are 2 requirements for coloring output:

1. It's supported on the platform
2. The user wants it: `IRB.conf[:USE_COLORIZE] == true`

Right now we check 1 and 2 separately whenever we colorize things.
But it's error-prone because while 1 is the default of `colorable`
parameter, 2 always need to manually checked. When 2 is overlooked, it
causes issues like https://github.com/ruby/irb/pull/362

And there's 0 case where we may want to colorize even when the user
disables it. So I think we should merge 2 into `Color.colorable?` so it
can be automatically picked up.

* Add tests for all inspect modes

* Simplify inspectors' coloring logic

* Replace use_colorize? with Color.colorable?

* Remove Context#use_colorize cause it's redundant

https://github.com/ruby/irb/commit/1c53023ac4