Improve method completion for string and regexp that includes word break characters

[tompng]

Description

fixes #314

In these case, irb cannot correctly complete string and regexp methods.

• "()".
• "hello world".
• /hello world/.

This pull request fixes it.

Background

Readline and Reline has a configuration completer_quote_characters and completer_word_break_characters of completion target.
It was able to calculate "()". completion target correctly.

In this pull request(#212), Reline.completer_quote_characters = '' is added, which means reline does not consider quotes in completion target calculation.
Completion target calculated by reline changed from "hello world". to world". and the regexp needed to be updated.

Change

I changed string completion regexp to match anything". I also changed regexp for regexp completion.
Since array completion regexp matches to ]., changing string completion regexp to match ". is acceptable(in my opinion).

[st0012]

Completion target calculated by reline changed from "hello world". to world".

Is it possible to resolve the issue by assigning proper completer_quote_characters? This behaviour doesn't seem intuitive to me.

If it does not match, it will fallback to showing all-methods that searches ObjectSpace. Avoiding it will improve performance a little bit.

This should probably be updated.

[tompng]

Is it possible to resolve the issue by assigning proper completer_quote_characters?

I think it's not possible now. If I add Reline.completer_quote_characters = %('"), closing quote is automatically added and will be impossible to input. I didn't figure it out whether it's a reline's bug or just configuration missing.

movie.mp4

[tompng]

This should probably be updated.

OK 👍 I removed the assert_not_inlcude

[st0012]

Hmm it looks like a reline's bug, or completer_quote_characters has very limited use cases if that's intentional.
Can you add comments before the changed regexps to give readers some context?